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preproc: add conditional-string smacro parameters; simplify functions

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Add the option of having strings only conditionally quoted (&&) -- do
not quote an already quoted string again -- as opposed to always
quoting a string.

This makes a lot of the string functions way simpler to implement, and
removes the need to share ad hoc parsing code with directives.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin
2022-11-21 10:47:08 -08:00
parent 30ff4f92c0
commit 516fbba03e
2 changed files with 110 additions and 87 deletions
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29
doc/nasmdoc.src
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@@ -2424,17 +2424,22 @@ A single pair of parentheses is a subcase of a single, unused argument:
This is similar to the behavior of the C preprocessor.
\b If declared with an \c{=}, NASM will evaluate the argument as an
expression after expansion.
\b If declared with an \c{=}, NASM will expand the argument and then
evaluate it as a numeric expression.
\b If an argument declared with an \c{&}, a macro parameter will be
turned into a quoted string after expansion.
\b If declared with an \c{&}, NASM will expand the argument and then
turn into a quoted string; if the argument already \e{is} a quoted
string, it will be quoted again.
\b If declared with \c{&&}, NASM will expand the argument and then
turn it into a quoted string, but if the argument already is a quoted
string, it will \e{not} be re-quoted.
\b If declared with a \c{+}, it is a greedy or variadic parameter; it
includes any subsequent commas and parameters.
will include any subsequent commas and parameters.
\b If declared with an \c{!}, NASM will not strip whitespace and
braces (useful in conjunction with \c{&}).
braces (potentially useful in conjunction with \c{&} or \c{&&}.)
For example:
@@ -2849,7 +2854,9 @@ means "until N-1 characters before the end of string", i.e. \c{-1}
means until end of string, \c{-2} until one character before, etc.
The corresponding preprocessor function is \c{%substr()}, see
\k{f_substr}.
\k{f_substr}, however please note that the default value for the
length parameter, if omitted, is \c{-1} rather than \c{1} for
\c{%substr()}.
\H{ppfunc} \i{Preprocessor Functions}
@@ -3016,13 +3023,17 @@ in the same way the \i\c{%strlen} directive would, see \k{strlen}.
The \c{%substr()} function extracts a substring of a quoted string, in
the same way the \i\c{%substr} directive would, see \k{substr}. Note
that unlike the \c{%substr} directive, a comma is required after the
string argument.
that unlike the \c{%substr} directive, commas are required between all
parameters, is required after the string argument, and that the
default for the length argument, if omitted, is \c{-1} (i.e. the
remainder of the string) rather than \c{1}.
\c ; The following lines are all equivalent
\c %define mychar 'yzw'
\c %substr mychar 'xyzw' 2,-1
\c %xdefine mychar %substr('xyzw',2,3)
\c %xdefine mychar %substr('xyzw',2,-1)
\c %xdefine mychar %substr('xyzw',2)
\S{f_tok} \i\c{%tok()} function