From 5b6fc836137be0073e1a15895c6375429762c147 Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Tue, 5 Jul 2011 22:43:42 -0400
Subject: [PATCH] Kill the "horizontal" declarator chain.

The "next" pointer in declarators is used in exactly one place: the list
of declarators of a declaration.  Move this chain to the toplevel so
that we get a list of declarations instead: now every struct cdecl has
exatly one declarator.

This helps eliminate the nasty hack in "explain" to print multiple
declarators.
---
 src/cdecl.h   |  4 +++-
 src/cdecl99.c | 10 ++--------
 src/parse.y   | 45 ++++++++++++++++++++++++++++++---------------
 3 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/src/cdecl.h b/src/cdecl.h
index 883a4e4..95d7634 100644
--- a/src/cdecl.h
+++ b/src/cdecl.h
@@ -48,6 +48,8 @@ enum {
 };
 
 struct cdecl {
+	struct cdecl *next;
+
 	struct cdecl_declspec {
 		struct cdecl_declspec *next;
 		unsigned type;
@@ -55,7 +57,7 @@ struct cdecl {
 	} *specifiers;
 
 	struct cdecl_declarator {
-		struct cdecl_declarator *next, *child;
+		struct cdecl_declarator *child;
 		unsigned type;
 		union {
 			char *ident;
diff --git a/src/cdecl99.c b/src/cdecl99.c
index d966805..639edea 100644
--- a/src/cdecl99.c
+++ b/src/cdecl99.c
@@ -40,21 +40,15 @@ static int cmd_explain(char *cmd, char *arg)
 	static char *buf;
 
 	struct cdecl *decl;
-	struct cdecl_declarator *d;
 	size_t rc;
 
 	decl = cdecl_parse_decl(arg);
 	if (!decl)
 		goto out;
 
-	for (d = decl->declarators; d; d = d->next) {
-		struct cdecl decl_tmp = {
-			.specifiers  = decl->specifiers,
-			.declarators = d,
-		};
-
+	for (struct cdecl *i = decl; i; i = i->next) {
 retry:
-		rc = cdecl_explain(buf, bufsz, &decl_tmp);
+		rc = cdecl_explain(buf, bufsz, i);
 		if (rc >= bufsz) {
 			char *tmp;
 
diff --git a/src/parse.y b/src/parse.y
index 7d4c3dc..86091f9 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -76,8 +76,10 @@ static void free_declspec(struct cdecl_declspec *x)
 static void free_declarator(struct cdecl_declarator *x)
 {
 	struct cdecl_declarator *p;
+
 	while (x) {
-		p = x->next;
+		p = x->child;
+
 		switch (x->type) {
 		case CDECL_DECL_NULL:
 			break;
@@ -94,23 +96,31 @@ static void free_declarator(struct cdecl_declarator *x)
 			assert(0);
 		}
 
-		free_declarator(x->child);
 		free(x);
 		x = p;
 	}
 }
 
-static void free_decl(struct cdecl *decl)
+static void free_decl(struct cdecl *x)
 {
-	free_declspec(decl->specifiers);
-	free_declarator(decl->declarators);
-	free(decl);
+	struct cdecl *p;
+
+	while (x) {
+		p = x->next;
+
+		/* The specifiers may be shared by an entire chain. */
+		if (!p || p->specifiers != x->specifiers)
+			free_declspec(x->specifiers);
+
+		free_declarator(x->declarators);
+		free(x);
+		x = p;
+	}
 }
 
 void cdecl_free(struct cdecl *decl)
 {
-	if (decl)
-		free_decl(decl);
+	free_decl(decl);
 }
 %}
 
@@ -165,8 +175,8 @@ void cdecl_free(struct cdecl *decl)
 %type <declspec>   declspec_notype declspec_noid typespec_noid typespec
 %type <declspec>   qualifier qualifiers
 %type <declspec>   declspecs declspecs_noid
-%type <declarator> direct_declarator declarator declarators pointer array
-%type <decl>       declaration
+%type <declarator> direct_declarator declarator pointer array
+%type <decl>       declaration declarators declarator_wrap
 
 %%
 
@@ -175,9 +185,10 @@ input: declaration {
 };
 
 declaration: declspecs declarators T_SEMICOLON {
-	ALLOC_STRUCT($$, struct cdecl,
-		.specifiers = $1,
-		.declarators = $2);
+	$$ = $2;
+
+	for (struct cdecl *i = $$; i; i = i->next)
+		i->specifiers = $1;
 };
 
 declspecs: declspec_notype declspecs {
@@ -198,10 +209,14 @@ qualifiers: { $$ = NULL; } | qualifiers qualifier {
 	$$->next = $1;
 }
 
-declarators: declarator | declarator T_COMMA declarators {
+declarators: declarator_wrap | declarator_wrap T_COMMA declarators {
 	$$ = $1;
 	$$->next = $3;
-};
+}
+
+declarator_wrap: declarator {
+	ALLOC_STRUCT($$, struct cdecl, .declarators = $1);
+}
 
 declspec_simple: T_AUTO { $$ = CDECL_STOR_AUTO;     }
 	| T_TYPEDEF     { $$ = CDECL_STOR_TYPEDEF;  }
-- 
2.43.2