X-Git-Url: https://git.draconx.ca/gitweb/cdecl99.git/blobdiff_plain/31ac11cc668bb8ecc1317fd2e8bd79b7925bceeb..9cb5aae31e1c126970843ef9b6e54036b185fd51:/src/explain.c

diff --git a/src/explain.c b/src/explain.c
index 1b46d20..10a7064 100644
--- a/src/explain.c
+++ b/src/explain.c
@@ -1,6 +1,6 @@
 /*
  *  Render C declarations as English.
- *  Copyright © 2011 Nick Bowler
+ *  Copyright © 2011, 2021, 2023-2024 Nick Bowler
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -15,148 +15,133 @@
  *  You should have received a copy of the GNU General Public License
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+
 #include <config.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdarg.h>
-#include <stdbool.h>
-#include <assert.h>
+#include <inttypes.h>
 
 #include "cdecl.h"
-#include "output.h"
+#include "cdecl-internal.h"
+
+#define PRE_SPECS (CDECL_SPEC_FUNC|CDECL_SPEC_STOR)
+#define POST_SPECS (CDECL_SPEC_QUAL|CDECL_SPEC_TYPE)
+
+static void explain_specs(struct output_state *dst, struct cdecl_declspec *s, unsigned mask)
+{
+	cdecl__emit(dst, cdecl__emit_specs(dst, s, mask));
+}
 
 /*
- * Renders the start of the thing being declared.  If top is true, print
- * the "declare" or "type" keywords at the front, as appropriate.
+ * If declarator declares an identifier foo, then emit "foo as "; otherwise
+ * emit nothing.
  */
-static size_t
-explain_prologue(char *buf, size_t n, struct cdecl_declarator *d, bool top)
+static void
+explain_name(struct output_state *dst, struct cdecl_declarator *d)
 {
-	size_t ret = 0, rc = 0;
-
-	while (d) {
-		switch (d->type) {
-		case CDECL_DECL_NULL:
-			if (top)
-				return snprintf(buf, n, "type");
-			return 0;
-		case CDECL_DECL_IDENT:
-			if (top)
-				rc = snprintf(buf, n, "declare");
-			ret += cdecl__advance(&buf, &n, rc);
-			return ret + snprintf(buf, n, "%s as", d->u.ident);
-		}
-
+	while (d->child)
 		d = d->child;
-	}
 
-	assert(0);
+	if (d->type == CDECL_DECL_IDENT) {
+		cdecl__emit(dst, d->u.ident);
+		cdecl__emit(dst, " as ");
+	}
 }
 
-static size_t
-explain_pointer(char *buf, size_t n, struct cdecl_pointer *p)
+/*
+ * For a pointer declarator, emit "[QUAL ]pointer to ", where
+ * QUAL is the (possibly empty) list of qualifiers.
+ */
+static void
+explain_pointer(struct output_state *dst, struct cdecl_pointer *p)
 {
-	size_t ret = 0, rc;
-
-	rc = cdecl__explain_specs(buf, n, p->qualifiers, CDECL_SPEC_QUAL);
-	ret += cdecl__advance(&buf, &n, rc);
-
-	return ret + snprintf(buf, n, "pointer to");
+	explain_specs(dst, p->qualifiers, -1);
+	cdecl__emit(dst, "pointer to ");
 }
 
-static size_t
-explain_array(char *buf, size_t n, struct cdecl_array *a)
+/*
+ * For an array declarator, emit "[variable-length ]array [X ]of ", where
+ * for a variable-length array X is the (possibly omitted) identifier name,
+ * and for normal arrays X is the (possibly omitted) length.
+ */
+static void
+explain_array(struct output_state *dst, struct cdecl_array *a)
 {
-	size_t ret = 0, rc = 0;
-
-	if (a->vla)
-		rc = snprintf(buf, n, "variable-length array");
-	else
-		rc = snprintf(buf, n, "array");
-	ret += cdecl__advance(&buf, &n, rc);
+	size_t rc = 0;
 
+	cdecl__emit(dst, "variable-length array " + (a->vla ? 0 : 16));
 	if (a->vla) {
-		rc = snprintf(buf, n, "%s", a->vla);
-		ret += cdecl__advance(&buf, &n, rc);
-	} else if (a->length) {
-		rc = snprintf(buf, n, "%ju", a->length);
-		ret += cdecl__advance(&buf, &n, rc);
+		rc = cdecl__emit(dst, a->vla);
+	} else {
+		rc = cdecl__emit_uint(dst, a->length);
 	}
-
-	return ret + snprintf(buf, n, "of");
+	cdecl__emit(dst, " of " + !rc);
 }
 
-static size_t
-explain_declarators(char *buf, size_t n, struct cdecl_declarator *decl);
+static void
+explain_declarators(struct output_state *dst, struct cdecl_declarator *decl);
 
-static size_t explain_decl(char *buf, size_t n, struct cdecl *decl, bool top)
+static void explain_decl(struct output_state *dst, struct cdecl *decl)
 {
-	size_t ret = 0, rc;
-
-	rc = explain_prologue(buf, n, decl->declarators, top);
-	ret += cdecl__advance(&buf, &n, rc);
-
-	rc = cdecl__explain_pre_specs(buf, n, decl->specifiers);
-	ret += cdecl__advance(&buf, &n, rc);
-
-	rc = explain_declarators(buf, n, decl->declarators);
-	ret += cdecl__advance(&buf, &n, rc);
-
-	return ret + cdecl__explain_post_specs(buf, n, decl->specifiers);
+	explain_name(dst, decl->declarators);
+	explain_specs(dst, decl->specifiers, PRE_SPECS);
+	explain_declarators(dst, decl->declarators);
+	cdecl__emit_specs(dst, decl->specifiers, POST_SPECS);
 }
 
-static size_t explain_function(char *buf, size_t n, struct cdecl_function *f)
+/*
+ * For a function declarator, emit "function [PARAM ]returning ", where
+ * PARAM is the (omitted in the case of an empty non-prototype identifier
+ * list) parameter or identifier lists enclosed in parentheses.
+ */
+static void
+explain_function(struct output_state *dst, struct cdecl_function *f)
 {
-	size_t ret = 0, rc = 0;
-
-	rc = snprintf(buf, n, "function");
-	ret += cdecl__advance(&buf, &n, rc);
+	int tail_offset = 7;
 
+	cdecl__emit(dst, "function ");
 	if (f->parameters) {
-		rc = snprintf(buf, n, "(");
-		ret += cdecl__advance_(&buf, &n, rc);
+		struct cdecl *p;
 
-		for (struct cdecl *p = f->parameters; p; p = p->next) {
-			rc = explain_decl(buf, n, p, false);
-			ret += cdecl__advance_(&buf, &n, rc);
+		cdecl__emit(dst, "(");
 
+		for (p = f->parameters; p; p = p->next) {
+			explain_decl(dst, p);
 			if (p->next)
-				rc = snprintf(buf, n, ",");
-			else if (f->variadic)
-				rc = snprintf(buf, n, ", ...)");
-			else
-				rc = snprintf(buf, n, ")");
-			ret += cdecl__advance(&buf, &n, rc);
+				cdecl__emit(dst, ", ");
 		}
-	}
 
-	return ret + snprintf(buf, n, "returning");
+		tail_offset = f->variadic ? 0 : 5;
+	}
+	cdecl__emit(dst, ", ...) returning " + tail_offset);
 }
 
-static size_t
-explain_declarators(char *buf, size_t n, struct cdecl_declarator *d)
+static void
+explain_declarators(struct output_state *dst, struct cdecl_declarator *d)
 {
-	size_t ret = 0, rc;
-
-	if (d->type == CDECL_DECL_IDENT || d->type == CDECL_DECL_NULL)
-		return 0;
-
-	rc = explain_declarators(buf, n, d->child);
-	ret += cdecl__advance(&buf, &n, rc);
+	if (d->child)
+		explain_declarators(dst, d->child);
 
 	switch (d->type) {
 	case CDECL_DECL_POINTER:
-		return ret + explain_pointer(buf, n, &d->u.pointer);
+		explain_pointer(dst, &d->u.pointer);
+		return;
 	case CDECL_DECL_ARRAY:
-		return ret + explain_array(buf, n, &d->u.array);
+		explain_array(dst, &d->u.array);
+		return;
 	case CDECL_DECL_FUNCTION:
-		return ret + explain_function(buf, n, &d->u.function);
-	default:
-		assert(0);
+		explain_function(dst, &d->u.function);
+		return;
 	}
 }
 
 size_t cdecl_explain(char *buf, size_t n, struct cdecl *decl)
 {
-	return explain_decl(buf, n, decl, true);
+	struct output_state dst = { buf, n };
+
+	if (cdecl_is_abstract(decl->declarators))
+		cdecl__emit(&dst, "type ");
+	else
+		cdecl__emit(&dst, "declare ");
+
+	explain_decl(&dst, decl);
+	return dst.accum;
 }