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Diffstat (limited to 'doc')
-rw-r--r-- | doc/info/mds.texinfo | 110 |
1 files changed, 107 insertions, 3 deletions
diff --git a/doc/info/mds.texinfo b/doc/info/mds.texinfo index a78852a..d5162d3 100644 --- a/doc/info/mds.texinfo +++ b/doc/info/mds.texinfo @@ -5174,7 +5174,7 @@ line feeds for new lines. * Keyboard Layout Identification:: Specifing the layout language, country and variant. * Layout Assumptions:: Making assumption about the keyboard layout. * Include Statement:: Including base files. -* Layout Macros:: Reducing repetition. +* Layout Macros and Functions:: Reducing repetition. @end menu @@ -5549,8 +5549,8 @@ include "../common/base" -@node Layout Macros -@subsection Layout Macros +@node Layout Macros and Functions +@subsection Layout Macros and Functions There is a lot of repetitive work in layouts, for instance all letters need mapping for any combination of use of @@ -5644,6 +5644,110 @@ end for instead of using the alternation-trick. +You call also use if-statments. For example + +@example +for "à" to "þ" as \1 + # times sign is not upper case of division sign + if \not(\equals(\a "\u00F7")) + letter(\1 \add(\sub(\1 "à") "À")) + end if +end for +@end example + +or equivalently + +@example +for "à" to "þ" as \1 + if \equals(\a "\u00F7") + continue # times sign is not upper case of division sign + end if + letter(\1 \add(\sub(\1 "à") "À")) +end for +@end example + +@code{continue} can be used to stop the iteration of +the innermost for-loop and skip to the next iteration. +You can also use @code{break}, but it also has the +effect to stop the entire loop. Similarly, @code{return} +can be used to break an entire macro call, or function +call. + +You can also use @code{if} for more example things, +and use @code{else if} and @code{else if}: + +@example +macro latter/1 + if \not(\greater(\1 "z")) + letter(\1 \add(\sub(\1 "a") "A")) + else if \not(\greater(\1 "þ")) + letter(\1 \add(\sub(\1 "à") "À")) + else + letter(\1 \sub(\1 1)) + end if +end macro +@end example + +Note that there is no quotes around the `a' +in @code{letter(\1 \sub(\1 1))}. This means +that the argument will be than value 1 rather +than the code point of the character `1'. Note +however that values lower than zero or equals +to or greater than 2 to the power of 31 not +allowed and can either cause compile-time +error or erroneous compiled files. + +Functions are similar to function macros, +the difference is that a function is called +inline and is prefixed with slash, and rather +than inline the code inside it, the evalutes +to the last value it evaluted before it returned. + +For example instead of @code{\not(\greater(\1 "z"))} +you can write @code{\less_eq(\1 "z")} after you +have defined the function `less_eq/2' with the +following code: + +@example +function less_eq/2 + \not(\greater(\1 \2)) +end function +@end example + +A final constract to make layout code less +repetitive is let-statements. This can be +used to assign values to variables, and +declar variables in undefined. Variable names +can only be numerical and most not start with +a zero. @code{\0} is not valid variable name. + +The code + +@example +macro latter/1 + if \not(\greater(\1 "z")) + letter(\1 \add(\sub(\1 "a") "A")) + else if \not(\greater(\1 "þ")) + letter(\1 \add(\sub(\1 "à") "À")) + else + letter(\1 \sub(\1 1)) + end if +end macro +@end example + +can equivalently be writen using @code{let} as + +@example +macro latter/1 + let \2 : 1 + if \not(\greater(\1 "z")) + let \2 : \sub("a" "A") + else if \not(\greater(\1 "þ")) + let \2 : \sub("à" "À") + end if + letter(\1 \sub(\1 \2)) +end macro +@end example |