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3. AutoGen Template

The AutoGen template file defines the content of the output text. It is composed of two parts. The first part consists of a pseudo macro invocation and commentary. It is followed by the template proper.

This pseudo macro is special. It is used to identify the file as a AutoGen template file, fixing the starting and ending marks for the macro invocations in the rest of the file, specifying the list of suffixes to be generated by the template and, optionally, the shell to use for processing shell commands embedded in the template.

AutoGen-ing a file consists of copying text from the template to the output file until a start macro marker is found. The text from the start marker to the end marker constitutes the macro text. AutoGen macros may cause sections of the template to be skipped or processed several times. The process continues until the end of the template is reached. The process is repeated once for each suffix specified in the pseudo macro.

This chapter describes the format of the AutoGen template macros and the usage of the AutoGen native macros. Users may augment these by defining their own macros. See section 3.6.4 DEFINE - Define a user AutoGen macro.

3.1 Format of the Pseudo Macro  
3.2 Naming a value  
3.3 Macro Expression Syntax  
3.4 AutoGen Scheme Functions  
3.5 Common Scheme Functions  
3.6 AutoGen Native Macros  
3.7 Redirecting Output  

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3.1 Format of the Pseudo Macro

The pseudo-macro starts with up to seven (7) punctuation characters used for the template start-macro marker, followed by the autogen magic marker (autogen5), the template marker (template), zero or more suffix specifications, scheme expressions and the end-macro marker. It may also consist of up to seven (7) punctuation characters. Interspersed may be comment lines (blank lines or lines starting with a hash mark [#]) and edit mode markers (text between pairs of -*- characters).

As an example, assume we want to use [+ and +] as the start and end macro markers, and we wish to produce a `.c' and a `.h' file, then the first macro invocation will look something like this:

 
[+ AutoGen5 template -*- Mode: emacs-mode-of-choice -*-
h=chk-%s.h
c
# make sure we don't use csh:
(setenv "SHELL" "/bin/sh")  +]

Note It is generally a good idea to use some sort of opening bracket in the starting macro and closing bracket in the ending macro (e.g. {, (, [, or even < in the starting macro). It helps both visually and with editors capable of finding a balancing parenthesis. The closing marker may not begin with an open parenthesis, as that is used to enclose a scheme expression.

It is also helpful to avoid using the comment marker (#); the POSIXly acceptable file name characters period (.), hyphen (-) and underscore (_); and finally, it is advisable to avoid using any of the quote characters double, single or back-quote. But there is no special check for any of these advisories.

Detailed description:

The starting macro marker must be the first non-white space characters encountered in the file. The marker consists of all the contiguous ASCII punctuation characters found there. With optional intervening white space, this marker must be immediately followed by the keywords, "autogen5" and "template". Capitalization of these words is not important. This is followed by zero, one or more suffix specifications and, possibly, a scheme expression.

Suffix specifications consist of a sequence of POSIX compliant file name characters and, optionally, an equal sign and a file name "printf"-style formatting string. Two string arguments are allowed for that string: the base name of the definition file and the current suffix (that being the text to the left of the equal sign). (Note "POSIX compliant file name characters" consist of alphanumerics plus the period (.), hyphen (-) and underscore (_) characters.) If there are no suffix specifications, then the generated file will be written to the stdout file descriptor.

The scheme expression is intended to allow the template writer to specify the shell program that must be used to interpret the shell commands in the template. It can have no effect on any shell commands in the definitions file, as that file will have been processed by the time the pseudo macro is interpreted. You can specify the shell as follows:

 
(setenv "SHELL" "/bin/sh")

This works because AutoGen examines the value of the SHELL environment variable in order to select the shell to run. If that shell is allowed to be csh, AutoGen will break. If it is allowed to be zsh, AutoGen may break. Your milage may vary.

The pseudo macro ends with an end macro marker. Like the starting macro marker, it consists of a contiguous sequence of arbitrary punctuation characters. However, additionally, it may not begin with any of the POSIX file name characters and it may not contain the start macro marker.

This pseudo macro may appear on one or several lines of text. Intermixed may be comment lines (completely blank or starting with the hash character # in column 1), and file content markers (text between -*- pairs on a single line). This may be used to establish editing "modes" for the file. These are ignored by AutoGen.

The template proper starts after the pseudo-macro. The starting character is either the first non-whitespace character or the first character after the new-line that follows the end macro marker.

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3.2 Naming a value

When an AutoGen value is specified in a template, it is specified by name. The name may be a simple name, or a compound name of several components. Since each named value in AutoGen is implicitly an array of one or more values, each component may have an index associated with it.

It looks like this:

 
comp-name-1 . comp-name-2 [ 2 ]

Note that if there are multiple components to a name, each component name is separated by a dot (.). Indexes follow a component name, enclosed in square brackets ([ and ]). The index may be either an integer or an integer-valued define name. The first component of the name is searched for in the current definition level. If not found, higher levels will be searched until either a value is found, or there are no more definition levels. Subsequent components of the name must be found within the context of the newly-current definition level. Also, if the named value is prefixed by a dot (.), then the value search is started in the current context only. No higher levels are searched.

If someone rewrites this, I'll incorporate it. :-)

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3.3 Macro Expression Syntax

AutoGen has two types of expressions: full expressions and basic ones. A full AutoGen expression can appear by itself, or as the argument to certain AutoGen built-in macros: CASE, IF, ELIF, INCLUDE, INVOKE (explicit invocation, see section 3.6.16 INVOKE - Invoke a User Defined Macro), and WHILE. If it appears by itself, the result is inserted into the output. If it is an argument to one of these macros, the macro code will act on it sensibly.

You are constrained to basic expressions only when passing arguments to user defined macros, See section 3.6.4 DEFINE - Define a user AutoGen macro.

The syntax of a full AutoGen expression is:

 
[[ <apply-code> ] <value-name> ] [ <basic-expr-1> [ <basic-expr-2> ]]

How the expression is evaluated depends upon the presence or absence of the apply code and value name. The "value name" is the name of an AutoGen defined value, or not. If it does not name such a value, the expression result is generally the empty string. All expressions must contain either a value-name or a basic-expr.

3.3.1 Apply Code  
3.3.2 Basic Expression  

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3.3.1 Apply Code

The "apply code" selected determines the method of evaluating the expression. There are five apply codes, including the non-use of an apply code.

`no apply code'
This is the most common expression type. Expressions of this sort come in three flavors:

`<value-name>'
The result is the value of value-name, if defined. Otherwise it is the empty string.

`<basic-expr>'
The result of the basic expression is the result of the full expression, See section 3.3.2 Basic Expression.

`<value-name> <basic-expr>'
If there is a defined value for value-name, then the basic-expr is evaluated. Otherwise, the result is the empty string.

`% <value-name> <basic-expr>'
If value-name is defined, use basic-expr as a format string for sprintf. Then, if the basic-expr is either a back-quoted string or a parenthesized expression, then hand the result to the appropriate interpreter for further evaluation. Otherwise, for single and double quote strings, the result is the result of the sprintf operation. Naturally, if value-name is not defined, the result is the empty string.

For example, assume that foo had the string value, bar:
 
[+ % foo `printf '%%x\\n' $%s` +]
This would cause the shell to evaluate "printf '%x\n' $bar". Assuming that the shell variable bar had a numeric value, the expression result would be that number, in hex. Note the need for doubled percent characters and backslashes.

`? <value-name> <basic-expr-1> <basic-expr-2>'
Two basic-expr-s are required. If the value-name is defined, then the first basic-expr-1 is evaluated, otherwise basic-expr-2 is.

`- <value-name> <basic-expr>'
Evaluate basic-expr only if value-name is not defined.

`?% <value-name> <basic-expr-1> <basic-expr-2>'
This combines the functions of `?' and `%'. If value-name is defined, it behaves exactly like `%', above, using basic-expr-1. If not defined, then basic-expr-2 is evaluated.

For example, assume again that foo had the string value, bar:
 
[+ ?% foo `cat $%s` `pwd` +]
This would cause the shell to evaluate "cat $bar". If foo were not defined, then the result would be the name of our current directory.

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3.3.2 Basic Expression

A basic expression can have one of the following forms:

`'STRING''
A single quoted string. Backslashes can be used to protect single quotes ('), hash characters (#), or backslashes (\) in the string. All other characters of STRING are output as-is when the single quoted string is evaluated. Backslashes are processed before the hash character for consistency with the definition syntax. It is needed there to avoid preprocessing conflicts.

`"STRING"'
A double quoted string. This is a cooked text string as in C, except that they are not concatenated with adjacent strings. Evaluating "STRING" will output STRING with all backslash sequences interpreted.

``STRING`'
A back quoted string. When this expression is evaluated, STRING is first interpreted as a cooked string (as in `"STRING"') and evaluated as a shell expression by the AutoGen server shell. This expression is replaced by the stdout output of the shell.

`(STRING)'
A parenthesized expression. It will be passed to the Guile interpreter for evaluation and replaced by the resulting value.

Additionally, other than in the % and ?% expressions, the Guile expressions may be introduced with the Guile comment character (;) and you may put a series of Guile expressions within a single macro. They will be implicitly evaluated as if they were arguments to the (begin ...) expression. The result will be the the result of the last Guile expression evaluated.

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3.4 AutoGen Scheme Functions

AutoGen uses Guile to interpret Scheme expressions within AutoGen macros. All of the normal Guile functions are available, plus several extensions (see section 3.5 Common Scheme Functions) have been added to augment the repertoire of string manipulation functions and manage the state of AutoGen processing.

This section describes those functions that are specific to AutoGen. Please take note that these AutoGen specific functions are not loaded and thus not made available until after the command line options have been processed and the AutoGen definitions have been loaded. They may, of course, be used in Scheme functions that get defined at those times, but they cannot be invoked.

3.4.1 `ag-function?' - test for function  
3.4.2 `base-name' - base output name  
3.4.3 `count' - definition count  
3.4.4 `def-file' - definitions file name  
3.4.5 `dne' - "Do Not Edit" warning  
3.4.6 `error' - display message and exit  
3.4.7 `error-source-line' - display of file & line  
3.4.8 `exist?' - test for value name  
3.4.9 `first-for?' - detect first iteration  
3.4.10 `for-by' - set iteration step  
3.4.11 `for-from' - set initial index  
3.4.12 `for-index' - get current loop index  
3.4.13 `for-sep' - set loop separation string  
3.4.14 `for-to' - set ending index  
3.4.15 `get' - get named value  
3.4.16 `high-lim' - get highest value index  
3.4.17 `last-for?' - detect last iteration  
3.4.18 `len' - get count of values  
3.4.19 `low-lim' - get lowest value index  
3.4.20 `match-value?' - test for matching value  
3.4.21 `out-delete' - delete current output file  
3.4.22 `out-depth' - output file stack depth  
3.4.23 `out-move' - change name of output file  
3.4.24 `out-name' - current output file name  
3.4.25 `out-pop' - close current output file  
3.4.26 `out-push-add' - append output to file  
3.4.27 `out-push-new' - purge and create output file  
3.4.28 `out-resume' - resume current output file  
3.4.29 `out-suspend' - suspend current output file  
3.4.30 `out-switch' - close and create new output  
3.4.31 `set-writable' - Make the output file be writable  
3.4.32 `stack' - make list of AutoGen values  
3.4.33 `suffix' - get the current suffix  
3.4.34 `tpl-file' - get the template file name  
3.4.35 `tpl-file-line' - get the template file and line number  

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3.4.1 `ag-function?' - test for function

Usage: (ag-function? ag-name)
return SCM_BOOL_T if a specified name is a user-defined AutoGen macro, otherwise return SCM_BOOL_F.

Arguments:
ag-name - name of AutoGen macro

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3.4.2 `base-name' - base output name

Usage: (base-name)
Returns a string containing the base name of the output file(s). Generally, this is also the base name of the definitions file.

This Scheme function takes no arguments.

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3.4.3 `count' - definition count

Usage: (count ag-name)
Count the number of entries for a definition. The input argument must be a string containing the name of the AutoGen values to be counted. If there is no value associated with the name, the result is an SCM immediate integer value of zero.

Arguments:
ag-name - name of AutoGen value

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3.4.4 `def-file' - definitions file name

Usage: (def-file)
Get the name of the definitions file. Returns the name of the source file containing the AutoGen definitions.

This Scheme function takes no arguments.

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3.4.5 `dne' - "Do Not Edit" warning

Usage: (dne prefix [ first_prefix ])
Generate a "DO NOT EDIT" or "EDIT WITH CARE" warning string. Which depends on whether or not the --writable command line option was set. The first argument is a per-line string prefix. The optional second argument is a prefix for the first-line and, in read-only mode, activates the editor hints:
 
-*- buffer-read-only: t -*- vi: set ro:

Arguments:
prefix - string for starting each output line
first_prefix - Optional - for the first output line

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3.4.6 `error' - display message and exit

Usage: (error message)
The argument is a string that printed out as part of an error message. The message is formed from the formatting string:

 
DEFINITIONS ERROR in %s line %d for %s:  %s\n

The first three arguments to this format are provided by the routine and are: The name of the template file, the line within the template where the error was found, and the current output file name.

After displaying the message, the current output file is removed and autogen exits with the EXIT_FAILURE error code. IF, however, the argument begins with the number 0 (zero), or the string is the empty string, then processing continues with the next suffix.

Arguments:
message - message to display before exiting

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3.4.7 `error-source-line' - display of file & line

Usage: (error-source-line)
This function is only invoked just before Guile displays an error message. It displays the file name and line number that triggered the evaluation error. You should not need to invoke this routine directly. Guile will do it automatically.

This Scheme function takes no arguments.

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3.4.8 `exist?' - test for value name

Usage: (exist? ag-name)
return SCM_BOOL_T iff a specified name has an AutoGen value. The name may include indexes and/or member names. All but the last member name must be an aggregate definition. For example:
 
(exist? "foo[3].bar.baz")
will yield true if all of the following is true:
There is a member value of either group or string type named baz for some group value bar that is a member of the foo group with index 3. There may be multiple entries of bar within foo, only one needs to contain a value for baz.

Arguments:
ag-name - name of AutoGen value

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3.4.9 `first-for?' - detect first iteration

Usage: (first-for? [ for_var ])
Returns SCM_BOOL_T if the named FOR loop (or, if not named, the current innermost loop) is on the first pass through the data. Outside of any FOR loop, it returns SCM_UNDEFINED. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
for_var - Optional - which for loop

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3.4.10 `for-by' - set iteration step

Usage: (for-by by)
This function records the "step by" information for an AutoGen FOR function. Outside of the FOR macro itself, this function will emit an error. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
by - the iteration increment for the AutoGen FOR macro

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3.4.11 `for-from' - set initial index

Usage: (for-from from)
This function records the initial index information for an AutoGen FOR function. Outside of the FOR macro itself, this function will emit an error. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
from - the initial index for the AutoGen FOR macro

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3.4.12 `for-index' - get current loop index

Usage: (for-index [ for_var ])
Returns the current index for the named FOR loop. If not named, then the index for the innermost loop. Outside of any FOR loop, it returns SCM_UNDEFINED. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
for_var - Optional - which for loop

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3.4.13 `for-sep' - set loop separation string

Usage: (for-sep separator)
This function records the separation string that is to be inserted between each iteration of an AutoGen FOR function. This is often nothing more than a comma. Outside of the FOR macro itself, this function will emit an error.

Arguments:
separator - the text to insert between the output of each FOR iteration

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3.4.14 `for-to' - set ending index

Usage: (for-to to)
This function records the terminating value information for an AutoGen FOR function. Outside of the FOR macro itself, this function will emit an error. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
to - the final index for the AutoGen FOR macro

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3.4.15 `get' - get named value

Usage: (get ag-name)
Get the first string value associated with the name. It will always return either the associated string value, or the empty string.

Arguments:
ag-name - name of AutoGen value

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3.4.16 `high-lim' - get highest value index

Usage: (high-lim ag-name)
Returns the highest index associated with an array of definitions. This is generally, but not necessarily, one less than the count value. (The indexes may be specified, rendering a non-zero based or sparse array of values.)

This is very useful for specifying the size of a zero-based array of values where not all values are present. For example:

 
tMyStruct myVals[ [+ (+ 1 (high-lim "my-val-list")) +] ];

Arguments:
ag-name - name of AutoGen value

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3.4.17 `last-for?' - detect last iteration

Usage: (last-for? [ for_var ])
Returns SCM_BOOL_T if the named FOR loop (or, if not named, the current innermost loop) is on the last pass through the data. Outside of any FOR loop, it returns SCM_UNDEFINED. See section 3.6.13 FOR - Emit a template block multiple times.

Arguments:
for_var - Optional - which for loop

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3.4.18 `len' - get count of values

Usage: (len ag-name)
If the named object is a group definition, then "len" is the same as "count". Otherwise, if it is one or more text definitions, then it is the sum of their string lengths. If it is a single text definition, then it is equivalent to (string-length (get "ag-name")).

Arguments:
ag-name - name of AutoGen value

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3.4.19 `low-lim' - get lowest value index

Usage: (low-lim ag-name)
Returns the lowest index associated with an array of definitions.

Arguments:
ag-name - name of AutoGen value

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3.4.20 `match-value?' - test for matching value

Usage: (match-value? op ag-name test-str)
This function answers the question, "Is there an AutoGen value named ag-name with a value that matches the pattern test-str using the match function op?" Return SCM_BOOL_T iff at least one occurrence of the specified name has such a value. The operator can be any function that takes two string arguments and yields a boolean. It is expected that you will use one of the string matching functions provided by AutoGen.
The value name must follow the same rules as the ag-name argument for exist? (see section 3.4.8 `exist?' - test for value name).

Arguments:
op - boolean result operator
ag-name - name of AutoGen value
test-str - string to test against

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3.4.21 `out-delete' - delete current output file

Usage: (out-delete)
Remove the current output file. Cease processing the template for the current suffix. It is an error if there are push-ed output files. Use the (error "0") scheme function instead. See section 3.7 Redirecting Output.

This Scheme function takes no arguments.

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3.4.22 `out-depth' - output file stack depth

Usage: (out-depth)
Returns the depth of the output file stack. See section 3.7 Redirecting Output.

This Scheme function takes no arguments.

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3.4.23 `out-move' - change name of output file

Usage: (out-move new-name)
Rename current output file. See section 3.7 Redirecting Output. Please note: changing the name will not save a temporary file from being deleted. It may, however, be used on the root output file.

Arguments:
new-name - new name for the current output file

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3.4.24 `out-name' - current output file name

Usage: (out-name)
Returns the name of the current output file. If the current file is a temporary, unnamed file, then it will scan up the chain until a real output file name is found. See section 3.7 Redirecting Output.

This Scheme function takes no arguments.

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3.4.25 `out-pop' - close current output file

Usage: (out-pop [ disp ])
If there has been a push on the output, then close that file and go back to the previously open file. It is an error if there has not been a push. See section 3.7 Redirecting Output.

If there is no argument, no further action is taken. Otherwise, the argument should be #t and the contents of the file are returned by the function.

Arguments:
disp - Optional - return contents of the file

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3.4.26 `out-push-add' - append output to file

Usage: (out-push-add file-name)
Identical to push-new, except the contents are not purged, but appended to. See section 3.7 Redirecting Output.

Arguments:
file-name - name of the file to append text to

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3.4.27 `out-push-new' - purge and create output file

Usage: (out-push-new [ file-name ])
Leave the current output file open, but purge and create a new file that will remain open until a pop delete or switch closes it. The file name is optional and, if omitted, the output will be sent to a temporary file that will be deleted when it is closed. See section 3.7 Redirecting Output.

Arguments:
file-name - Optional - name of the file to create

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3.4.28 `out-resume' - resume current output file

Usage: (out-resume suspName)
If there has been a suspended output, then make that output descriptor current again. That output must have been suspended with the same tag name given to this routine as its argument.

Arguments:
suspName - A name tag for reactivating

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3.4.29 `out-suspend' - suspend current output file

Usage: (out-suspend suspName)
If there has been a push on the output, then set aside the output descriptor for later reactiviation with (out-resume "xxx"). The tag name need not reflect the name of the output file. In fact, the output file may be an anonymous temporary file. You may also change the tag every time you suspend output to a file, because the tag names are forgotten as soon as the file has been "resumed".

Arguments:
suspName - A name tag for reactivating

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3.4.30 `out-switch' - close and create new output

Usage: (out-switch file-name)
Switch output files - close current file and make the current file pointer refer to the new file. This is equivalent to out-pop followed by out-push-new, except that you may not pop the base level output file, but you may switch it. See section 3.7 Redirecting Output.

Arguments:
file-name - name of the file to create

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3.4.31 `set-writable' - Make the output file be writable

Usage: (set-writable [ set? ])
This function will set the current output file to be writable (or not). This is only effective if neither the --writable nor --not-writable have been specified. This state is reset when the current suffix's output is complete.

Arguments:
set? - Optional - boolean arg, false to make output non-writable

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3.4.32 `stack' - make list of AutoGen values

Usage: (stack ag-name)
Create a scheme list of all the strings that are associated with a name. They must all be text values or we choke.

Arguments:
ag-name - AutoGen value name

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3.4.33 `suffix' - get the current suffix

Usage: (suffix)
Returns the current active suffix. See generate in the Declarations Input section above.

This Scheme function takes no arguments.

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3.4.34 `tpl-file' - get the template file name

Usage: (tpl-file)
Returns the name of the current template file.

This Scheme function takes no arguments.

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3.4.35 `tpl-file-line' - get the template file and line number

Usage: (tpl-file-line [ msg-fmt ])
Returns the file and line number of the current template macro using either the default format, "from %s line %d", or else the format you supply. For example, if you want only the line number, you would supply the format "%2$d".

Arguments:
msg-fmt - Optional - formatting for line message

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3.5 Common Scheme Functions

This section describes a number of general purpose functions that make the kind of string processing that AutoGen does a little easier. Unlike the AutoGen specific functions (see section 3.4 AutoGen Scheme Functions), these functions are available for direct use during definition load time.

3.5.1 `bsd' - Free BSD public license  
3.5.2 `c-string' - emit string for ANSI C  
3.5.3 `extract' - extract text from another file  
3.5.4 `find-file' - locate a file in the search path  
3.5.5 `fprintf' - format to a file  
3.5.6 `gperf' - perform a perfect hash function  
3.5.7 `gpl' - GNU public license  
3.5.8 `in?' - test for string in list  
3.5.9 `join' - join string list with separator  
3.5.10 `kr-string' - emit string for K&R C  
3.5.11 `lgpl' - GNU lib public license  
3.5.12 `license' - an arbitrary license  
3.5.13 `make-gperf' - build a perfect hash function program  
3.5.14 `max' - maximum value in list  
3.5.15 `min' - minimum value in list  
3.5.16 `prefix' - prefix lines with a string  
3.5.17 `printf' - format to stdout  
3.5.18 `raw-shell-str' - single quote shell string  
3.5.19 `shell' - invoke a shell script  
3.5.20 `shell-str' - double quote shell string  
3.5.21 `shellf' - format a string, run shell  
3.5.22 `sprintf' - format a string  
3.5.23 `string-capitalize' - make a new string be capitalized  
3.5.24 `string-capitalize!' - capitalize a string  
3.5.25 `string-contains-eqv?' - caseless substring  
3.5.26 `string-contains?' - substring match  
3.5.27 `string-downcase' - make a new string be lower case  
3.5.28 `string-downcase!' - make a string be lower case  
3.5.29 `string-end-eqv-match?' - caseless regex ending  
3.5.30 `string-end-match?' - regex match end  
3.5.31 `string-ends-eqv?' - caseless string ending  
3.5.32 `string-ends-with?' - string ending  
3.5.33 `string-equals?' - string matching  
3.5.34 `string-eqv-match?' - caseless regex match  
3.5.35 `string-eqv?' - caseless string match  
3.5.36 `string-has-eqv-match?' - caseless regex contains  
3.5.37 `string-has-match?' - contained regex match  
3.5.38 `string-match?' - regex match  
3.5.39 `string-start-eqv-match?' - caseless regex start  
3.5.40 `string-start-match?' - regex match start  
3.5.41 `string-starts-eqv?' - caseless string start  
3.5.42 `string-starts-with?' - string starting  
3.5.43 `string->c-name!' - map non-name chars to underscore  
3.5.44 `string-tr!' - convert characters  
3.5.45 `string-upcase' - make a new string be upper case  
3.5.46 `string-upcase!' - make a string be upper case  
3.5.47 `sub-shell-str' - back quoted (sub-)shell string  
3.5.48 `sum' - sum of values in list  

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3.5.1 `bsd' - Free BSD public license

Usage: (bsd prog_name owner prefix)
Emit a string that contains the Free BSD Public License. It takes three arguments: prefix contains the string to start each output line. owner contains the copyright owner. prog_name contains the name of the program the copyright is about.

Arguments:
prog_name - name of the program under the BSD
owner - Grantor of the BSD License
prefix - String for starting each output line

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3.5.2 `c-string' - emit string for ANSI C

Usage: (c-string string)
Reform a string so that, when printed, the C compiler will be able to compile the data and construct a string that contains exactly what the current string contains. Many non-printing characters are replaced with escape sequences. Newlines are replaced with a backslash, an n, a closing quote, a newline, seven spaces and another re-opening quote. The compiler will implicitly concatenate them. The reader will see line breaks.

A K&R compiler will choke. Use kr-string for that compiler.

Arguments:
string - string to reformat

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3.5.3 `extract' - extract text from another file

Usage: (extract file-name marker-fmt [ caveat ] [ default ])
This function is used to help construct output files that may contain text that is carried from one version of the output to the next.

The first two arguments are required, the second are optional:

The resulting strings are presumed to be unique within the subject file. As a simplified example:

 
[+ (extract "fname" "// %s - SOMETHING - %s" ""
"example default") +]
will result in the following text being inserted into the output:

 
// START - SOMETHING - DO NOT CHANGE THIS COMMENT
example default
// END   - SOMETHING - DO NOT CHANGE THIS COMMENT
The "example default" string can then be carried forward to the next generation of the output, provided the output is not named "fname" and the old output is renamed to "fname" before AutoGen-eration begins.

NOTE:
You can set aside previously generated source files inside the pseudo macro with a Guile/scheme function, extract the text you want to keep with this extract function. Just remember you should delete it at the end, too. Here is an example from my Finite State Machine generator:

 
[+ AutoGen5 Template  -*- Mode: text -*-
h=%s-fsm.h   c=%s-fsm.c
(shellf
"[ -f %1$s-fsm.h ] && mv -f %1$s-fsm.h .fsm.head
[ -f %1$s-fsm.c ] && mv -f %1$s-fsm.c .fsm.code" (base-name)) +]

This code will move the two output files name, ".fsm.head" and ".fsm.code". At the end of the 'c' output processing, I delete them.

Arguments:
file-name - name of file with text
marker-fmt - format for marker text
caveat - Optional - warn about changing marker
default - Optional - default initial text

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3.5.4 `find-file' - locate a file in the search path

Usage: (find-file file-name [ suffix ])
AutoGen has a search path that it uses to locate template and definition files. This function will search the same list for `file-name', both with and without the `.suffix', if provided.

Arguments:
file-name - name of file with text
suffix - Optional - file suffix to try, too

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3.5.5 `fprintf' - format to a file

Usage: (fprintf port format [ format-arg ... ])
Format a string using arguments from the alist. Write to a specified port. The result will NOT appear in your output. Use this to print information messages to a template user.

Arguments:
port - Guile-scheme output port
format - formatting string
format-arg - Optional - list of arguments to formatting string

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3.5.6 `gperf' - perform a perfect hash function

Usage: (gperf name str)
Perform the perfect hash on the input string. This is only useful if you have previously created a gperf program with the make-gperf function See section 3.5.13 `make-gperf' - build a perfect hash function program. The name you supply here must match the name used to create the program and the string to hash must be one of the strings supplied in the make-gperf string list. The result will be a perfect hash index.

See the documentation for gperf(1GNU) for more details.

Arguments:
name - name of hash list
str - string to hash

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3.5.7 `gpl' - GNU public license

Usage: (gpl prog-name prefix)
Emit a string that contains the GNU Public License. It takes two arguments: prefix contains the string to start each output line, and prog_name contains the name of the program the copyright is about.

Arguments:
prog-name - name of the program under the GPL
prefix - String for starting each output line

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3.5.8 `in?' - test for string in list

Usage: (in? test-string string-list ...)
Return SCM_BOOL_T if the first argument string is found in one of the entries in the second (list-of-strings) argument.

Arguments:
test-string - string to look for
string-list - list of strings to check

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3.5.9 `join' - join string list with separator

Usage: (join separator list ...)
With the first argument as the separator string, joins together an a-list of strings into one long string. The list may contain nested lists, partly because you cannot always control that.

Arguments:
separator - string to insert between entries
list - list of strings to join

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3.5.10 `kr-string' - emit string for K&R C

Usage: (kr-string string)
Reform a string so that, when printed, a K&R C compiler will be able to compile the data and construct a string that contains exactly what the current string contains. Many non-printing characters are replaced with escape sequences. New-lines are replaced with a backslash-n-backslash and newline sequence,

Arguments:
string - string to reformat

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3.5.11 `lgpl' - GNU lib public license

Usage: (lgpl prog_name owner prefix)
Emit a string that contains the GNU Library Public License. It takes three arguments: prefix contains the string to start each output line. owner contains the copyright owner. prog_name contains the name of the program the copyright is about.

Arguments:
prog_name - name of the program under the LGPL
owner - Grantor of the LGPL (obsolete)
prefix - String for starting each output line

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3.5.12 `license' - an arbitrary license

Usage: (license lic_name prog_name owner prefix)
Emit a string that contains the named license. The license text is read from a file named, lic_name.lic, searching the standard directories. The file contents are used as a format argument to printf(3), with prog_name and owner as the two string formatting arguments. Each output line is automatically prefixed with the string prefix.

Arguments:
lic_name - file name of the license
prog_name - name of the licensed program or library
owner - Grantor of the License
prefix - String for starting each output line

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3.5.13 `make-gperf' - build a perfect hash function program

Usage: (make-gperf name strings ...)
Build a program to perform perfect hashes of a known list of input strings. This function produces no output, but prepares a program named, `gperf_<name>' for use by the gperf function See section 3.5.6 `gperf' - perform a perfect hash function.

This program will be obliterated within a few seconds after AutoGen exits.

Arguments:
name - name of hash list
strings - list of strings to hash

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3.5.14 `max' - maximum value in list

Usage: (max list ...)
Return the maximum value in the list

Arguments:
list - list of values. Strings are converted to numbers

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3.5.15 `min' - minimum value in list

Usage: (min list ...)
Return the minimum value in the list

Arguments:
list - list of values. Strings are converted to numbers

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3.5.16 `prefix' - prefix lines with a string

Usage: (prefix prefix text)
Prefix every line in the second string with the first string.

For example, if the first string is "# " and the second contains:
 
two
lines
The result string will contain:
 
# two
# lines

Arguments:
prefix - string to insert at start of each line
text - multi-line block of text

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3.5.17 `printf' - format to stdout

Usage: (printf format [ format-arg ... ])
Format a string using arguments from the alist. Write to the default output port. The result will NOT appear in your output. Use this to print information messages to a template user.

Arguments:
format - formatting string
format-arg - Optional - list of arguments to formatting string

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3.5.18 `raw-shell-str' - single quote shell string

Usage: (raw-shell-str string)
Convert the text of the string into a singly quoted string that a normal shell will process into the original string. (It will not do macro expansion later, either.) Contained single quotes become tripled, with the middle quote escaped with a backslash. Normal shells will reconstitute the original string.

NOTE: some shells will not correctly handle unusual non-printing characters. This routine works for most reasonably conventional ASCII strings.

Arguments:
string - string to transform

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3.5.19 `shell' - invoke a shell script

Usage: (shell command)
Generate a string by writing the value to a server shell and reading the output back in. The template programmer is responsible for ensuring that it completes within 10 seconds. If it does not, the server will be killed, the output tossed and a new server started.

Arguments:
command - shell command - the result value is stdout

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3.5.20 `shell-str' - double quote shell string

Usage: (shell-str string)
Convert the text of the string into a double quoted string that a normal shell will process into the original string, almost. It will add the escape character \\ before two special characters to accomplish this: the backslash \\ and double quote ".

NOTE: some shells will not correctly handle unusual non-printing characters. This routine works for most reasonably conventional ASCII strings.

WARNING:
This function omits the extra backslash in front of a backslash, however, if it is followed by either a backquote or a dollar sign. It must do this because otherwise it would be impossible to protect the dollar sign or backquote from shell evaluation. Consequently, it is not possible to render the strings "\\$" or "\\`". The lesser of two evils.

All others characters are copied directly into the output.

The sub-shell-str variation of this routine behaves identically, except that the extra backslash is omitted in front of " instead of `. You have to think about it. I'm open to suggestions.

Meanwhile, the best way to document is with a detailed output example. If the backslashes make it through the texinfo processing correctly, below you will see what happens with three example strings. The first example string contains a list of quoted foos, the second is the same with a single backslash before the quote characters and the last is with two backslash escapes. Below each is the result of the raw-shell-str, shell-str and sub-shell-str functions.

 
foo[0]       = 'foo' "foo" `foo` $foo
raw-shell-str: ''\''foo'\'' "foo" `foo` $foo'
shell-str:     "'foo' \"foo\" `foo` $foo"
sub-shell-str: `'foo' "foo" \`foo\` $foo`

foo[1]       = \'bar\' \"bar\" \`bar\` \$bar
raw-shell-str: '\'\''bar\'\'' \"bar\" \`bar\` \$bar'
shell-str:     "\\'bar\\' \\"bar\\" \`bar\` \$bar"
sub-shell-str: `\\'bar\\' \"bar\" \\`bar\\` \$bar`

foo[2]       = \\'BAZ\\' \\"BAZ\\" \\`BAZ\\` \\$BAZ
raw-shell-str: '\\'\''BAZ\\'\'' \\"BAZ\\" \\`BAZ\\` \\$BAZ'
shell-str:     "\\\\'BAZ\\\\' \\\\"BAZ\\\\" \\\`BAZ\\\` \\\$BAZ"
sub-shell-str: `\\\\'BAZ\\\\' \\\"BAZ\\\" \\\\`BAZ\\\\` \\\$BAZ`

There should be triple and quadruple backslashes in the last two lines of the example. If this was not accurately reproduced, take a look at the agen5/test/shell.test test. Notice the backslashes in front of the dollar signs. It goes from zero to one to three for the "cooked" string examples.

Arguments:
string - string to transform

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3.5.21 `shellf' - format a string, run shell

Usage: (shellf format [ format-arg ... ])
Format a string using arguments from the alist, then send the result to the shell for interpretation.

Arguments:
format - formatting string
format-arg - Optional - list of arguments to formatting string

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3.5.22 `sprintf' - format a string

Usage: (sprintf format [ format-arg ... ])
Format a string using arguments from the alist.

Arguments:
format - formatting string
format-arg - Optional - list of arguments to formatting string

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3.5.23 `string-capitalize' - make a new string be capitalized

Usage: (string-capitalize str)
Create a new SCM string containing the same text as the original, only all the first letter of each word is upper cased and all other letters are made lower case.

Arguments:
str - input string

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3.5.24 `string-capitalize!' - capitalize a string

Usage: (string-capitalize! str)
capitalize all the words in an SCM string.

Arguments:
str - input/output string

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3.5.25 `string-contains-eqv?' - caseless substring

Usage: (*=* text match)
string-contains-eqv?: Test to see if a string contains an equivalent string. `equivalent' means the strings match, but without regard to character case and certain characters are considered `equivalent'. Viz., '-', '_' and '^' are equivalent.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.26 `string-contains?' - substring match

Usage: (*==* text match)
string-contains?: Test to see if a string contains a substring. "strstr(3)" will find an address.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.27 `string-downcase' - make a new string be lower case

Usage: (string-downcase str)
Create a new SCM string containing the same text as the original, only all the upper case letters are changed to lower case.

Arguments:
str - input string

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3.5.28 `string-downcase!' - make a string be lower case

Usage: (string-downcase! str)
Change to lower case all the characters in an SCM string.

Arguments:
str - input/output string

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3.5.29 `string-end-eqv-match?' - caseless regex ending

Usage: (*~ text match)
string-end-eqv-match?: Test to see if a string ends with a pattern. Case is not significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.30 `string-end-match?' - regex match end

Usage: (*~~ text match)
string-end-match?: Test to see if a string ends with a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.31 `string-ends-eqv?' - caseless string ending

Usage: (*= text match)
string-ends-eqv?: Test to see if a string ends with an equivalent string.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.32 `string-ends-with?' - string ending

Usage: (*== text match)
string-ends-with?: Test to see if a string ends with a substring. strcmp(3) returns zero for comparing the string ends.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.33 `string-equals?' - string matching

Usage: (== text match)
string-equals?: Test to see if two strings exactly match.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.34 `string-eqv-match?' - caseless regex match

Usage: (~ text match)
string-eqv-match?: Test to see if a string fully matches a pattern. Case is not significant, but any character equivalences must be expressed in your regular expression.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.35 `string-eqv?' - caseless string match

Usage: (= text match)
string-eqv?: Test to see if two strings are equivalent. `equivalent' means the strings match, but without regard to character case and certain characters are considered `equivalent'. Viz., '-', '_' and '^' are equivalent. If the arguments are not strings, then the result of the numeric comparison is returned.

This is an overloaded operation. If the arguments are not both strings, then the query is passed through to scm_num_eq_p().

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.36 `string-has-eqv-match?' - caseless regex contains

Usage: (*~* text match)
string-has-eqv-match?: Test to see if a string contains a pattern. Case is not significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.37 `string-has-match?' - contained regex match

Usage: (*~~* text match)
string-has-match?: Test to see if a string contains a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.38 `string-match?' - regex match

Usage: (~~ text match)
string-match?: Test to see if a string fully matches a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.39 `string-start-eqv-match?' - caseless regex start

Usage: (~* text match)
string-start-eqv-match?: Test to see if a string starts with a pattern. Case is not significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.40 `string-start-match?' - regex match start

Usage: (~~* text match)
string-start-match?: Test to see if a string starts with a pattern. Case is significant.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.41 `string-starts-eqv?' - caseless string start

Usage: (=* text match)
string-starts-eqv?: Test to see if a string starts with an equivalent string.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.42 `string-starts-with?' - string starting

Usage: (==* text match)
string-starts-with?: Test to see if a string starts with a substring.

Arguments:
text - text to test for pattern
match - pattern/substring to search for

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3.5.43 `string->c-name!' - map non-name chars to underscore

Usage: (string->c-name! str)
Change all the graphic characters that are invalid in a C name token into underscores. Whitespace characters are ignored. Any other character type (i.e. non-graphic and non-white) will cause a failure.

Arguments:
str - input/output string

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3.5.44 `string-tr!' - convert characters

Usage: (string-tr! source match translation)
This is the same as the tr(1) program, except the string to transform is the first argument. The second and third arguments are used to construct mapping arrays for the transformation of the first argument.

It is too bad this little program has so many different and incompatible implementations!

Arguments:
source - string to transform
match - characters to be converted
translation - conversion list

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3.5.45 `string-upcase' - make a new string be upper case

Usage: (string-upcase str)
Create a new SCM string containing the same text as the original, only all the lower case letters are changed to upper case.

Arguments:
str - input string

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3.5.46 `string-upcase!' - make a string be upper case

Usage: (string-upcase! str)
Change to upper case all the characters in an SCM string.

Arguments:
str - input/output string

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3.5.47 `sub-shell-str' - back quoted (sub-)shell string

Usage: (sub-shell-str string)
This function is substantially identical to shell-str, except that the quoting character is ` and the "leave the escape alone" character is ".

Arguments:
string - string to transform

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3.5.48 `sum' - sum of values in list

Usage: (sum list ...)
Compute the sum of the list of expressions.

Arguments:
list - list of values. Strings are converted to numbers

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3.6 AutoGen Native Macros

This section describes the various AutoGen natively defined macros. Unlike the Scheme functions, some of these macros are "block macros" with a scope that extends through a terminating macro. Block macros must not overlap. That is to say, a block macro started within the scope of an encompassing block macro must have its matching end macro appear before the encompassing block macro is either ended or subdivided.

The block macros are these:

CASE
This macro has scope through the ESAC macro. The scope is subdivided by SELECT macros. You must have at least one SELECT macro.

DEFINE
This macro has scope through the ENDDEF macro. The defined user macro can never be a block macro.

FOR
This macro has scope through the ENDFOR macro.

IF
This macro has scope through the ENDIF macro. The scope may be subdivided by ELIF and ELSE macros. Obviously, there may be only one ELSE macro and it must be the last of these subdivisions.

INCLUDE
This macro has the scope of the included file. It is a block macro in the sense that the included file must not contain any incomplete block macros.

WHILE
This macro has scope through the ENDWHILE macro.
3.6.1 AutoGen Macro Syntax  
3.6.2 CASE - Select one of several template blocks  
3.6.3 COMMENT - A block of comment to be ignored  
3.6.4 DEFINE - Define a user AutoGen macro  
3.6.5 ELIF - Alternate Conditional Template Block  
3.6.6 ELSE - Alternate Template Block  
3.6.7 ENDDEF - Ends a macro definition.  
3.6.8 ENDFOR - Terminates the FOR function template block  
3.6.9 ENDIF - Terminate the IF Template Block  
3.6.10 ENDWHILE - Terminate the WHILE Template Block  
3.6.11 ESAC - Terminate the CASE Template Block  
3.6.12 EXPR - Evaluate and emit an Expression  
3.6.13 FOR - Emit a template block multiple times  
3.6.14 IF - Conditionally Emit a Template Block  
3.6.15 INCLUDE - Read in and emit a template block  
3.6.16 INVOKE - Invoke a User Defined Macro  
3.6.17 SELECT - Selection block for CASE function  
3.6.18 UNKNOWN - Either a user macro or a value name.  
3.6.19 WHILE - Conditionally loop over a Template Block  
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3.6.1 AutoGen Macro Syntax

The general syntax is:

 
[ { <native-macro-name> | <user-defined-name> } ] [ <arg> ... ]

The syntax for <arg> depends on the particular macro, but is generally a full expression (see section 3.3 Macro Expression Syntax). Here are the exceptions to that general rule:

  1. INVOKE macros, implicit or explicit, must be followed by a list of name/string value pairs. The string values are simple expressions, as described above.

    That is, the INVOKE syntax is either:
     
    <user-macro-name> [ <name> [ = <expression> ] ... ]
    or
     
    INVOKE <name-expression> [ <name> [ = <expression> ] ... ]

  2. AutoGen FOR macros must be in one of two forms:

     
    FOR <name> [ <separator-string> ]
    or
     
    FOR <name> (...Scheme expression list)
    where <name> must be a simple name and the Scheme expression list is expected to contain one or more of the for-from, for-to, for-by, and for-sep functions. (See section 3.6.13 FOR - Emit a template block multiple times, and 3.4 AutoGen Scheme Functions)

  3. AutoGen DEFINE macros must be followed by a simple name. Anything after that is ignored. See section 3.6.4 DEFINE - Define a user AutoGen macro.

  4. The AutoGen COMMENT, ELSE, ESAC and the END* macros take no arguments and ignore everything after the macro name (e.g. see 3.6.3 COMMENT - A block of comment to be ignored)

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3.6.2 CASE - Select one of several template blocks

The arguments are evaluated and converted to a string, if necessary. (see section 3.6.12 EXPR - Evaluate and emit an Expression) The scope of the macro is up to the matching ESAC function. Within the scope of a CASE, this string is matched against case selection macros. There are sixteen match macros that are derived from four different ways the test may be performed, plus an "always true" match. The code for each selection expression is formed as follows:

  1. Must the match start matching from the beginning of the string? If not, then the match macro code starts with an asterisk (*).
  2. Must the match finish matching at the end of the string? If not, then the match macro code ends with an asterisk (*).
  3. Is the match a pattern match or a string comparison? If a comparison, use an equal sign (=). If a pattern match, use a tilde (~).
  4. Is the match case sensitive? If alphabetic case is important, double the tilde or equal sign.
  5. Do you need a default match when none of the others match? Use a single asterisk (*).

For example:

 
[+ CASE <full-expression> +]
[+ ~~*  "[Tt]est" +]reg exp must match at start, not at end
[+ ==   "TeSt"    +]a full-string, case sensitive compare
[+ =    "TEST"    +]a full-string, case insensitive compare
[+ *              +]always match - no testing
[+ ESAC +]

<full-expression> (see section 3.3 Macro Expression Syntax) may be any expression, including the use of apply-codes and value-names. If the expression yields a number, it is converted to a decimal string.

These case selection codes have also been implemented as Scheme expression functions using the same codes (see section 3.5 Common Scheme Functions).

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3.6.3 COMMENT - A block of comment to be ignored

If the native macro name code is #, then the entire macro function is treated as a comment and ignored.

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3.6.4 DEFINE - Define a user AutoGen macro

This function will define a new macro. You must provide a name for the macro. You do not specify any arguments, though the invocation may specify a set of name/value pairs that are to be active during the processing of the macro.

 
[+ define foo +]
... macro body with macro functions ...
[+ enddef +]
... [+ foo bar='raw text' baz=<<text expression>> +]

Once the macro has been defined, this new macro can be invoked by specifying the macro name as the first token after the start macro marker. Alternatively, you may make the invocation explicitly invoke a defined macro by specifying INVOKE in the macro invocation. If you do that, the macro name can be computed with an expression that gets evaluated every time the INVOKE macro is encountered. See section 3.6.16 INVOKE - Invoke a User Defined Macro.

Any remaining text in the macro invocation will be used to create new name/value pairs that only persist for the duration of the processing of the macro. The expressions are evaluated the same way basic expressions are evaluated. See section 3.3 Macro Expression Syntax.

The resulting definitions are handled much like regular definitions, except:

  1. The values may not be compound. That is, they may not contain nested name/value pairs.
  2. The bindings go away when the macro is complete.
  3. The name/value pairs are separated by whitespace instead of semi-colons.
  4. Sequences of strings are not concatenated.

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3.6.5 ELIF - Alternate Conditional Template Block

This macro must only appear after an IF function, and before any associated ELSE or ENDIF functions. It denotes the start of an alternate template block for the IF function. Its expression argument is evaluated as are the arguments to IF. For a complete description See section 3.6.14 IF - Conditionally Emit a Template Block.

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3.6.6 ELSE - Alternate Template Block

This macro must only appear after an IF function, and before the associated ENDIF function. It denotes the start of an alternate template block for the IF function. For a complete description See section 3.6.14 IF - Conditionally Emit a Template Block.

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3.6.7 ENDDEF - Ends a macro definition.

This macro ends the DEFINE function template block. For a complete description See section 3.6.4 DEFINE - Define a user AutoGen macro.

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3.6.8 ENDFOR - Terminates the FOR function template block

This macro ends the FOR function template block. For a complete description See section 3.6.13 FOR - Emit a template block multiple times.

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3.6.9 ENDIF - Terminate the IF Template Block

This macro ends the IF function template block. For a complete description See section 3.6.14 IF - Conditionally Emit a Template Block.

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3.6.10 ENDWHILE - Terminate the WHILE Template Block

This macro ends the WHILE function template block. For a complete description See section 3.6.19 WHILE - Conditionally loop over a Template Block.

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3.6.11 ESAC - Terminate the CASE Template Block

This macro ends the CASE function template block. For a complete description, See section 3.6.2 CASE - Select one of several template blocks.

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3.6.12 EXPR - Evaluate and emit an Expression

This macro does not have a name to cause it to be invoked explicitly, though if a macro starts with one of the apply codes or one of the simple expression markers, then an expression macro is inferred. The result of the expression evaluation (see section 3.3 Macro Expression Syntax) is written to the current output.

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3.6.13 FOR - Emit a template block multiple times

This macro has a slight variation on the standard syntax:
 
FOR <value-name> [ <separator-string> ]
or
 
FOR <value-name> (...Scheme expression list

The first argument must be the name of an AutoGen value. If there is no value associated with the name, the FOR loop block is skipped entirely. The scope of the FOR function extends to the corresponding ENDFOR macro.

If there are any further arguments, if the first character is either a semi-colon (;) or an opening parenthesis ((), then it is presumed to be a Scheme expression containing the FOR macro specific functions for-from, for-by, for-to, and/or for-sep. See section 3.4 AutoGen Scheme Functions. Otherwise, the remaining text is presumed to be a string for inserting between each iteration of the loop. This string will be emitted one time less than the number of iterations of the loop. That is, it is emitted after each loop, excepting for the last iteration.

If the from/by/to functions are invoked, they will specify which copies of the named value are to be processed. If there is no copy of the named value associated with a particular index, the FOR template block will be instantiated anyway. The template must use methods for detecting missing definitions and emitting default text. In this fashion, you can insert entries from a sparse or non-zero based array into a dense, zero based array.

NB: the for-from, for-to, for-by and for-sep functions are disabled outside of the context of the FOR macro. Likewise, the first-for, last-for and for-index functions are disabled outside of the range of a FOR block.

 
[+FOR var (for-from 0) (for-to <number>) (for-sep ",") +]
... text with various substitutions ...[+
ENDFOR var+]

this will repeat the ... text with various substitutions ... <number>+1 times. Each repetition, except for the last, will have a comma , after it.

 
[+FOR var ",\n" +]
... text with various substitutions ...[+
ENDFOR var +]

This will do the same thing, but only for the index values of var that have actually been defined.

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3.6.14 IF - Conditionally Emit a Template Block

Conditional block. Its arguments are evaluated (see section 3.6.12 EXPR - Evaluate and emit an Expression) and if the result is non-zero or a string with one or more bytes, then the condition is true and the text from that point until a matched ELIF, ELSE or ENDIF is emitted. ELIF introduces a conditional alternative if the IF clause evaluated FALSE and ELSE introduces an unconditional alternative.

 
[+IF <full-expression> +]
emit things that are for the true condition[+

ELIF <full-expression-2> +]
emit things that are true maybe[+

ELSE "This may be a comment" +]
emit this if all but else fails[+

ENDIF "This may *also* be a comment" +]

<full-expression> may be any expression described in the EXPR expression function, including the use of apply-codes and value-names. If the expression yields an empty string, it is interpreted as false.

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3.6.15 INCLUDE - Read in and emit a template block

The entire contents of the named file is inserted at this point. The contents of the file are processed for macro expansion. The arguments are eval-ed, so you may compute the name of the file to be included. The included file must not contain any incomplete function blocks. Function blocks are template text beginning with any of the macro functions `IF', `FOR', `WHILE', and `CASE' and extending through the respective terminating macro functions.

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3.6.16 INVOKE - Invoke a User Defined Macro

User defined macros may be invoked explicitly or implicitly. If you invoke one implicitly, the macro must begin with the name of the defined macro. Consequently, this may not be a computed value. If you explicitly invoke a user defined macro, the macro begins with the macro name INVOKE followed by a basic expression that must yield a known user defined macro. A macro name _must_ be found, or AutoGen will issue a diagnostic and exit.

Arguments are passed to the invoked macro by name. The text following the macro name must consist of a series of names each of which is followed by an equal sign (=) and a basic expression that yields a string.

The string values may contain template macros that are parsed the first time the macro is processed and evaluated again every time the macro is evaluated.

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3.6.17 SELECT - Selection block for CASE function

This macro selects a block of text by matching an expression against the sample text expression evaluated in the CASE macro. See section 3.6.2 CASE - Select one of several template blocks.

You do not specify a SELECT macro with the word "select". Instead, you must use one of the 17 match operators described in the CASE macro description.

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3.6.18 UNKNOWN - Either a user macro or a value name.

The macro text has started with a name not known to AutoGen. If, at run time, it turns out to be the name of a defined macro, then that macro is invoked. If it is not, then it is a conditional expression that is evaluated only if the name is defined at the time the macro is invoked.

You may not specify UNKNOWN explicitly.

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3.6.19 WHILE - Conditionally loop over a Template Block

Conditionally repeated block. Its arguments are evaluated (see section 3.6.12 EXPR - Evaluate and emit an Expression) and as long as the result is non-zero or a string with one or more bytes, then the condition is true and the text from that point until a matched ENDWHILE is emitted.

 
[+WHILE <full-expression> +]
emit things that are for the true condition[+

ENDWHILE +]

<full-expression> may be any expression described in the EXPR expression function, including the use of apply-codes and value-names. If the expression yields an empty string, it is interpreted as false.

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3.7 Redirecting Output

AutoGen provides a means for redirecting the template output to different files. It is accomplished by providing a set of Scheme functions named out-* (see section 3.4 AutoGen Scheme Functions).

These functions allow you to logically "push" output files onto a stack and return to previous files by "pop"ing them back off. At the end of processing the template for a particular suffix (see section 3.1 Format of the Pseudo Macro), all the files in the output stack are closed and popped off. Consequently, at the start of the processing of a template, there is only one output file on the stack. That file cannot be popped off.

There are also several functions for determining the output status. See section 3.4 AutoGen Scheme Functions.

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This document was generated by Bruce Korb on January, 7 2002 using texi2html