[src/trunk]: src/usr.bin/make make(1): split Var_Subst into easily understand...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/27f18f9daae9
branches:  trunk
changeset: 948332:27f18f9daae9
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Dec 27 11:03:00 2020 +0000

description:
make(1): split Var_Subst into easily understandable functions

Extracting the character-level details makes the essence of Var_Subst
visible in the code, which is to iterate over the given text, handling a
few types of tokens.

diffstat:

 usr.bin/make/var.c |  68 ++++++++++++++++++++++++++++++-----------------------
 1 files changed, 39 insertions(+), 29 deletions(-)

diffs (103 lines):

diff -r 0906ba81a35e -r 27f18f9daae9 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Sun Dec 27 10:53:23 2020 +0000
+++ b/usr.bin/make/var.c        Sun Dec 27 11:03:00 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.767 2020/12/27 10:53:23 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.768 2020/12/27 11:03:00 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -131,7 +131,7 @@
 #include "metachar.h"
 
 /*     "@(#)var.c      8.3 (Berkeley) 3/19/94" */
-MAKE_RCSID("$NetBSD: var.c,v 1.767 2020/12/27 10:53:23 rillig Exp $");
+MAKE_RCSID("$NetBSD: var.c,v 1.768 2020/12/27 11:03:00 rillig Exp $");
 
 typedef enum VarFlags {
        VAR_NONE        = 0,
@@ -4177,8 +4177,21 @@
 }
 
 static void
-VarSubstNested(const char **pp, Buffer *buf, GNode *ctxt,
-              VarEvalFlags eflags, Boolean *inout_errorReported)
+VarSubstDollarDollar(const char **pp, Buffer *res, VarEvalFlags eflags)
+{
+       /*
+        * A dollar sign may be escaped with another dollar
+        * sign.
+        */
+       if (save_dollars && (eflags & VARE_KEEP_DOLLAR))
+               Buf_AddByte(res, '$');
+       Buf_AddByte(res, '$');
+       *pp += 2;
+}
+
+static void
+VarSubstExpr(const char **pp, Buffer *buf, GNode *ctxt,
+            VarEvalFlags eflags, Boolean *inout_errorReported)
 {
        const char *p = *pp;
        const char *nested_p = p;
@@ -4229,6 +4242,22 @@
        *pp = p;
 }
 
+/*
+ * Skip as many characters as possible -- either to the end of the string
+ * or to the next dollar sign (variable expression).
+ */
+static void
+VarSubstPlain(const char **pp, Buffer *res)
+{
+       const char *p = *pp;
+       const char *start = p;
+
+       for (p++; *p != '$' && *p != '\0'; p++)
+               continue;
+       Buf_AddBytesBetween(res, start, p);
+       *pp = p;
+}
+
 /* Expand all variable expressions like $V, ${VAR}, $(VAR:Modifiers) in the
  * given string.
  *
@@ -4254,31 +4283,12 @@
        errorReported = FALSE;
 
        while (*p != '\0') {
-               if (p[0] == '$' && p[1] == '$') {
-                       /*
-                        * A dollar sign may be escaped with another dollar
-                        * sign.
-                        */
-                       if (save_dollars && (eflags & VARE_KEEP_DOLLAR))
-                               Buf_AddByte(&res, '$');
-                       Buf_AddByte(&res, '$');
-                       p += 2;
-
-               } else if (p[0] == '$') {
-                       VarSubstNested(&p, &res, ctxt, eflags, &errorReported);
-
-               } else {
-                       /*
-                        * Skip as many characters as possible -- either to
-                        * the end of the string or to the next dollar sign
-                        * (variable expression).
-                        */
-                       const char *plainStart = p;
-
-                       for (p++; *p != '$' && *p != '\0'; p++)
-                               continue;
-                       Buf_AddBytesBetween(&res, plainStart, p);
-               }
+               if (p[0] == '$' && p[1] == '$')
+                       VarSubstDollarDollar(&p, &res, eflags);
+               else if (p[0] == '$')
+                       VarSubstExpr(&p, &res, ctxt, eflags, &errorReported);
+               else
+                       VarSubstPlain(&p, &res);
        }
 
        *out_res = Buf_DestroyCompact(&res);