Initial support for explaining declarations.

This should support everything that the parser currently does.

diff --git a/Makefile.am b/Makefile.am
index 6b98b4ce099274fc70e2fd4518cfd28efece1191..83f5e600affc1a941d3ed4797651eb90cbd75e30 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -15,7 +15,8 @@ noinst_HEADERS = src/scan.h src/parse.h
 
 lib_LTLIBRARIES = libcdecl.la
 libcdecl_la_LDFLAGS = -export-symbols-regex '^cdecl_[[:lower:]]'
-libcdecl_la_SOURCES = src/scan.c src/parse.c src/parse-decl.c src/typemap.c
+libcdecl_la_SOURCES = src/scan.c src/parse.c src/parse-decl.c src/typemap.c \
+       src/explain.c
 
 bin_PROGRAMS = cdecl99
 cdecl99_SOURCES = src/cdecl99.c

diff --git a/src/cdecl.h b/src/cdecl.h
index 90a8804d3210aadbd5677fbbfabc9045d9bcf6d9..489be835284d65caf634d91f956d908a216edb69 100644 (file)
--- a/src/cdecl.h
+++ b/src/cdecl.h
@@ -1,6 +1,8 @@
 #ifndef CDECL_H_
 #define CEDCL_H_
 
+#include <stddef.h>
+
 /* Declaration specifier kinds. */
 enum {
        CDECL_SPEC_TYPE = 0,
@@ -58,6 +60,8 @@ struct cdecl {
 struct cdecl *cdecl_parse_decl(const char *declstr);
 void cdecl_free(struct cdecl *decl);
 
+size_t cdecl_explain(char *buf, size_t n, struct cdecl *decl);
+
 static inline int cdecl_spec_kind(struct cdecl_declspec *spec)
 {
        return spec->type & ~0xffu;

diff --git a/src/cdecl99.c b/src/cdecl99.c
index 6e15712780106619ebf226d9ed73d24e2e916eec..a0771912fe24acb404fe0df5790763be0d0b4a6c 100644 (file)
--- a/src/cdecl99.c
+++ b/src/cdecl99.c
@@ -36,11 +36,35 @@ static void print_help(void)
 
 static int cmd_explain(char *cmd, char *arg)
 {
+       static size_t bufsz;
+       static char *buf;
+
        struct cdecl *decl;
+       size_t rc;
 
        decl = cdecl_parse_decl(arg);
-       cdecl_free(decl);
+       if (!decl)
+               goto out;
+
+retry:
+       rc = cdecl_explain(buf, bufsz, decl);
+       if (rc >= bufsz) {
+               char *tmp;
+
+               tmp = realloc(buf, rc + 1);
+               if (!tmp) {
+                       fprintf(stderr, "failed to allocate memory\n");
+                       return 1;
+               }
 
+               buf = tmp;
+               bufsz = rc + 1;
+               goto retry;
+       }
+
+       printf("%s\n", buf);
+out:
+       cdecl_free(decl);
        return 1;
 }
 

diff --git a/src/explain.c b/src/explain.c
new file mode 100644 (file)
index 0000000..d7edc74
--- /dev/null
+++ b/src/explain.c
@@ -0,0 +1,149 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include "cdecl.h"
+#include "typemap.h"
+
+/* declare [ident] as [storage] [function specs] [other crap] [qualifiers] [type specs] */
+
+static size_t
+voutput(char *buf, size_t n, size_t off, const char *fmt, va_list ap)
+{
+       if (off >= n)
+               return vsnprintf(NULL, 0, fmt, ap);
+       return vsnprintf(buf+off, n-off, fmt, ap);
+}
+
+static size_t output(char *buf, size_t n, size_t off, const char *fmt, ...)
+{
+       va_list ap;
+       size_t ret;
+
+       va_start(ap, fmt);
+       ret = voutput(buf, n, off, fmt, ap);
+       va_end(ap);
+
+       return ret;
+}
+
+/* Renders the type qualifiers and type specifiers in canonical form. */
+static size_t
+explain_post_specs(char *buf, size_t n, struct cdecl_declspec *s)
+{
+       unsigned long qualmap = 0, typemap;
+       const char *tag = NULL;
+       size_t ret = 0;
+
+       typemap = cdecl__build_typemap(s);
+       if (typemap == -1)
+               return 0;
+
+       for (struct cdecl_declspec *c = s; c; c = c->next) {
+               switch (cdecl_spec_kind(c)) {
+               case CDECL_SPEC_QUAL:
+                       qualmap |= 1ul << (c->type & 0xff);
+                       break;
+               case CDECL_SPEC_TYPE:
+                       /* Valid C types have at most one identifier. */
+                       if (c->ident)
+                               tag = c->ident;
+                       break;
+               }
+       }
+
+       if (qualmap & (1ul << (CDECL_QUAL_RESTRICT & 0xff)))
+               ret += output(buf, n, ret, "restrict ");
+       if (qualmap & (1ul << (CDECL_QUAL_VOLATILE & 0xff)))
+               ret += output(buf, n, ret, "volatile ");
+       if (qualmap & (1ul << (CDECL_QUAL_CONST & 0xff)))
+               ret += output(buf, n, ret, "const ");
+
+       ret += output(buf, n, ret, "%s", cdecl__explain_typemap(typemap));
+       if (tag)
+               ret += output(buf, n, ret, " %s", tag);
+       return ret;
+}
+
+static const char *explain_storage(unsigned spec)
+{
+       switch (spec) {
+       case CDECL_STOR_TYPEDEF:
+               return "typedef";
+       case CDECL_STOR_EXTERN:
+               return "extern";
+       case CDECL_STOR_STATIC:
+               return "static";
+       case CDECL_STOR_AUTO:
+               return "auto";
+       case CDECL_STOR_REGISTER:
+               return "register";
+       default:
+               abort();
+       }
+}
+
+/* Renders the storage-class and function specifiers in canonical form. */
+static size_t explain_pre_specs(char *buf, size_t n, struct cdecl_declspec *s)
+{
+       unsigned long funcmap = 0;
+       const char *storage = NULL;
+       size_t ret = 0;
+
+       for (struct cdecl_declspec *c = s; c; c = c->next) {
+               switch (cdecl_spec_kind(c)) {
+               case CDECL_SPEC_FUNC:
+                       funcmap |= 1ul << (c->type & 0xff);
+                       break;
+               case CDECL_SPEC_STOR:
+                       /* Valid C declarations have at most one
+                        * storage-class specifier. */
+                       storage = explain_storage(c->type);
+                       break;
+               }
+       }
+
+       if (storage)
+               ret += output(buf, n, ret, "%s", storage);
+       if (funcmap & (1ul << (CDECL_FUNC_INLINE & 0xff)))
+               ret += output(buf, n, ret, "%.*s%s", !!ret, "", "inline");
+       return ret;
+}
+
+static size_t advance(char **buf, size_t *n, size_t amount)
+{
+       if (!amount)
+               return 0;
+
+       if (amount >= *n) {
+               *n   = 0;
+               *buf = 0;
+       } else {
+               (*buf)[amount] = ' ';
+               if (amount + 1 >= *n) {
+                       *buf = 0;
+                       *n = 0;
+               } else {
+                       *buf += amount + 1;
+                       *n   -= amount + 1;
+               }
+       }
+
+       return amount + 1;
+}
+
+size_t cdecl_explain(char *buf, size_t n, struct cdecl *decl)
+{
+       size_t ret = 0, rc;
+
+       /*
+        * XXX: This won't work when we add support for more complicated
+        * declarators.
+        */
+       rc = output(buf, n, 0, "declare %s as", decl->declarators->ident);
+       ret += advance(&buf, &n, rc);
+
+       rc = explain_pre_specs(buf, n, decl->specifiers);
+       ret += advance(&buf, &n, rc);
+
+       return ret + explain_post_specs(buf, n, decl->specifiers);
+}