Module Name: src
Committed By: rillig
Date: Wed Dec 30 14:28:32 UTC 2020
Modified Files:
src/usr.bin/make: for.c
Log Message:
make(1): improve .for loop documentation, clean up ForReadMore
The comma expression in ForReadMore may be a nice trick, but it's not as
easy to read as a simple if-then-else chain. Test for '{' before '('
since BSD makefiles use braces by convention.
To generate a diff of this commit:
cvs rdiff -u -r1.122 -r1.123 src/usr.bin/make/for.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/usr.bin/make/for.c
diff -u src/usr.bin/make/for.c:1.122 src/usr.bin/make/for.c:1.123
--- src/usr.bin/make/for.c:1.122 Wed Dec 30 10:03:16 2020
+++ src/usr.bin/make/for.c Wed Dec 30 14:28:32 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: for.c,v 1.122 2020/12/30 10:03:16 rillig Exp $ */
+/* $NetBSD: for.c,v 1.123 2020/12/30 14:28:32 rillig Exp $ */
/*
* Copyright (c) 1992, The Regents of the University of California.
@@ -32,24 +32,22 @@
/*-
* Handling of .for/.endfor loops in a makefile.
*
- * For loops are of the form:
+ * For loops have the form:
*
- * .for <varname...> in <value...>
- * ...
- * .endfor
- *
- * When a .for line is parsed, all following lines are accumulated into a
- * buffer, up to but excluding the corresponding .endfor line. To find the
- * corresponding .endfor, the number of nested .for and .endfor directives
- * are counted.
- *
- * During parsing, any nested .for loops are just passed through; they get
- * handled recursively in For_Eval when the enclosing .for loop is evaluated
- * in For_Run.
- *
- * When the .for loop has been parsed completely, the variable expressions
- * for the iteration variables are replaced with expressions of the form
- * ${:Uvalue}, and then this modified body is "included" as a special file.
+ * .for <varname...> in <value...>
+ * # the body
+ * .endfor
+ *
+ * When a .for line is parsed, the following lines are copied to the body of
+ * the .for loop, until the corresponding .endfor line is reached. In this
+ * phase, the body is not yet evaluated. This also applies to any nested
+ * .for loops.
+ *
+ * After reaching the .endfor, the values from the .for line are grouped
+ * according to the number of variables. For each such group, the unexpanded
+ * body is scanned for variable expressions, and those that match the variable
+ * names are replaced with expressions of the form ${:U...} or $(:U...).
+ * After that, the body is treated like a file from an .include directive.
*
* Interface:
* For_Eval Evaluate the loop in the passed line.
@@ -60,14 +58,14 @@
#include "make.h"
/* "@(#)for.c 8.1 (Berkeley) 6/6/93" */
-MAKE_RCSID("$NetBSD: for.c,v 1.122 2020/12/30 10:03:16 rillig Exp $");
+MAKE_RCSID("$NetBSD: for.c,v 1.123 2020/12/30 14:28:32 rillig Exp $");
static int forLevel = 0; /* Nesting level */
/* One of the variables to the left of the "in" in a .for loop. */
typedef struct ForVar {
char *name;
- size_t len;
+ size_t nameLen;
} ForVar;
/*
@@ -92,7 +90,7 @@ ForAddVar(For *f, const char *name, size
{
ForVar *var = Vector_Push(&f->vars);
var->name = bmake_strldup(name, len);
- var->len = len;
+ var->nameLen = len;
}
static void
@@ -354,8 +352,8 @@ Buf_AddEscaped(Buffer *cmds, const char
}
/*
- * While expanding the body of a .for loop, replace expressions like
- * ${i}, ${i:...}, $(i) or $(i:...) with their ${:U...} expansion.
+ * While expanding the body of a .for loop, replace the inner part of an
+ * expression like ${i} or ${i:...} or $(i) or $(i:...) with ":Uvalue".
*/
static void
SubstVarLong(For *f, const char **pp, const char **inout_mark, char ech)
@@ -365,14 +363,15 @@ SubstVarLong(For *f, const char **pp, co
for (i = 0; i < f->vars.len; i++) {
ForVar *forVar = Vector_Get(&f->vars, i);
- char *var = forVar->name;
- size_t vlen = forVar->len;
+ char *varname = forVar->name;
+ size_t varnameLen = forVar->nameLen;
- /* XXX: undefined behavior for p if vlen is longer than p? */
- if (memcmp(p, var, vlen) != 0)
+ /* XXX: undefined behavior for p if varname is longer than p? */
+ if (memcmp(p, varname, varnameLen) != 0)
continue;
/* XXX: why test for backslash here? */
- if (p[vlen] != ':' && p[vlen] != ech && p[vlen] != '\\')
+ if (p[varnameLen] != ':' && p[varnameLen] != ech &&
+ p[varnameLen] != '\\')
continue;
/* Found a variable match. Replace with :U<value> */
@@ -381,7 +380,7 @@ SubstVarLong(For *f, const char **pp, co
Buf_AddEscaped(&f->curBody,
f->items.words[f->sub_next + i], ech);
- p += vlen;
+ p += varnameLen;
*inout_mark = p;
break;
}
@@ -394,9 +393,10 @@ SubstVarLong(For *f, const char **pp, co
* variable expressions like $i with their ${:U...} expansion.
*/
static void
-SubstVarShort(For *f, char ch, const char **pp, const char **inout_mark)
+SubstVarShort(For *f, const char **pp, const char **inout_mark)
{
const char *p = *pp;
+ const char ch = *p;
size_t i;
/* Probably a single character name, ignore $$ and stupid ones. */
@@ -459,18 +459,18 @@ ForReadMore(void *v_arg, size_t *out_len
mark = Buf_GetAll(&f->body, NULL);
body_end = mark + Buf_Len(&f->body);
for (p = mark; (p = strchr(p, '$')) != NULL;) {
- char ch, ech;
- ch = *++p;
- if ((ch == '(' && (ech = ')', 1)) ||
- (ch == '{' && (ech = '}', 1))) {
+ if (p[1] == '{') {
+ p += 2;
+ SubstVarLong(f, &p, &mark, '}');
+ } else if (p[1] == '(') {
+ p += 2;
+ SubstVarLong(f, &p, &mark, ')');
+ } else if (p[1] != '\0') {
p++;
- SubstVarLong(f, &p, &mark, ech);
- continue;
- }
- if (ch == '\0')
+ SubstVarShort(f, &p, &mark);
+ } else
break;
- SubstVarShort(f, ch, &p, &mark);
}
Buf_AddBytesBetween(&f->curBody, mark, body_end);
