eeshow/kicad/sexpr.c, sexpr.h: simple parser for S-expressions

eeshow/Makefile

@@ -15,7 +15,7 @@ SHELL = /bin/bash
 NAME = eeshow
 OBJS = main.o version.o \
        kicad/sch-parse.o kicad/sch-render.o kicad/lib-parse.o \
-       kicad/lib-render.o kicad/dwg.o kicad/delta.o \
+       kicad/lib-render.o kicad/dwg.o kicad/delta.o kicad/sexpr.o \
        gui/gui.o gui/over.o gui/style.o gui/aoi.o gui/fmt-pango.o gui/input.o \
        gui/progress.o gui/glabel.o gui/sheet.o gui/history.o gui/render.o \
        gui/help.o gui/icons.o \

eeshow/kicad/sexpr.c

@@ -0,0 +1,335 @@
+/*
+ * kicad/sexpr.c - S-expression parser
+ *
+ * Written 2016 by Werner Almesberger
+ * Copyright 2016 by Werner Almesberger
+ *
+ * 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
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "misc/util.h"
+#include "misc/diag.h"
+#include "kicad/sexpr.h"
+
+
+struct stack {
+	struct expr **next;
+	struct stack *prev;
+};
+
+struct sexpr_ctx {
+	enum sexpr_state {
+		idle,
+		token,
+		string,
+		escape,
+		failed
+	} state;
+	struct expr *e;		/* expression */
+	const char *p;		/* beginning of string */
+	struct stack *sp;
+	struct stack stack;
+};
+
+
+/* ----- Parser ------------------------------------------------------------ */
+
+
+static void new_expr(struct sexpr_ctx *ctx)
+{
+	struct stack *st = alloc_type(struct stack);
+	struct expr *e = alloc_type(struct expr);
+
+	e->s = NULL;
+	e->e = NULL;
+	e->next = NULL;
+
+	*ctx->sp->next = e;
+	ctx->sp->next = &e->next;
+
+	st->prev = ctx->sp;
+	st->next = &e->e;
+	ctx->sp = st;
+}
+
+
+static void add_string(struct sexpr_ctx *ctx, const char *end)
+{
+	struct expr *e;
+	unsigned old;
+	unsigned new = end - ctx->p;
+
+	e = *ctx->sp->next;
+	if (e) {
+		old = strlen(e->s);
+	} else {
+		e = alloc_type(struct expr);
+		e->s = NULL;
+		e->e = NULL;
+		e->next = NULL;
+
+		*ctx->sp->next = e;
+		old = 0;
+	}
+
+	if (!new)
+		return;
+
+	e->s = realloc(e->s, old + new + 1);
+	if (!e->s)
+		diag_pfatal("realloc");
+	memcpy(e->s + old, ctx->p, new);
+	e->s[old + new] = 0;
+}
+
+
+static void end_string(struct sexpr_ctx *ctx, const char *end)
+{
+	struct expr *e;
+	char *s, *t;
+
+	add_string(ctx, end);
+	e = *ctx->sp->next;
+	ctx->sp->next = &e->next;
+
+	for (s = t = e->s; *s; s++) {
+		if (*s == '\\')
+			switch (*++s) {
+			case 'n':
+				*t++ = '\n';
+				continue;
+			case 't':
+				*t++ = '\t';
+				continue;
+			case 0:
+				abort();
+			default:
+				break;
+			}
+		*t++ = *s;
+	}
+	*t = 0;
+}
+
+
+bool sexpr_parse(struct sexpr_ctx *ctx, const char *s)
+{
+	ctx->p = s;
+	while (*s) {
+		switch (ctx->state) {
+		case idle:
+			switch (*s) {
+			case ' ':
+			case '\t':
+			case '\r':
+			case '\n':
+				break;
+			case '(':
+				new_expr(ctx);
+				break;
+			case ')':
+				if (!ctx->sp->prev) {
+					ctx->state = failed;
+					error("too many\n )");
+					break;
+				}
+				ctx->sp = ctx->sp->prev;
+				break;
+			case '"':
+				ctx->state = string;
+				ctx->p = s + 1;
+				break;
+			default:
+				ctx->p = s;
+				ctx->state = token;
+				break;
+			}
+			break;
+		case token:
+			switch (*s) {
+			case ' ':
+			case '\t':
+			case '\r':
+			case '\n':
+				ctx->state = idle;
+				end_string(ctx, s);
+				break;
+			case '(':
+			case ')':
+			case '"':
+				ctx->state = idle;
+				end_string(ctx, s);
+				continue;
+			default:
+				break;
+			}
+			break;
+		case string:
+			switch (*s) {
+			case '\r':
+			case '\n':
+				ctx->state = failed;
+				error("newline in string\n");
+				break;
+			case '"':
+				ctx->state = idle;
+				add_string(ctx, s);
+				break;
+			case '\\':
+				ctx->state = escape;
+				break;
+			default:
+				break;
+			}
+			break;
+		case escape:
+			switch (*s) {
+			case '\r':
+			case '\n':
+				ctx->state = failed;
+				error("newline in string\n");
+				break;
+			default:
+				ctx->state = string;
+				break;
+			}
+			break;
+		case failed:
+			return 0;
+		default:
+			abort();
+		}
+		s++;
+	}
+
+	switch (ctx->state) {
+	case token:
+	case string:
+	case escape:
+		add_string(ctx, s);
+		break;
+	default:
+		break;
+	}
+
+	return 1;
+}
+
+
+/* ----- Dumping ----------------------------------------------------------- */
+
+
+static void do_dump_expr(const struct expr *e, unsigned depth)
+{
+	bool need_nl = 0;
+
+	if (depth)
+		printf("%*s(", (depth - 1) * 2, "");
+	while (e) {
+		if (e->s) {
+			if (need_nl) {
+				printf("\n%*s", depth * 2, "");
+				need_nl = 0;
+			}
+			printf("\"%s\" ", e->s); /* @@@ escaping */
+		}
+		if (e->e) {
+			putchar('\n');
+			do_dump_expr(e->e, depth + 1);
+			need_nl = 1;
+		}
+		e = e->next;
+	}
+	if (depth)
+		putchar(')');
+}
+
+
+void dump_expr(const struct expr *e)
+{
+	do_dump_expr(e, 0);
+	putchar('\n');
+}
+
+
+/* ----- Cleanup ----------------------------------------------------------- */
+
+
+static void free_stack(struct sexpr_ctx *ctx)
+{
+	struct stack *prev;
+
+	while (ctx->sp != &ctx->stack) {
+		prev = ctx->sp->prev;
+		free(ctx->sp);
+		ctx->sp = prev;
+	}
+}
+
+
+void free_expr(struct expr *e)
+{
+	struct expr *next;
+
+	while (e) {
+		next = e->next;
+		if (e->s)
+			free(e->s);
+		else if (e->e)
+			free_expr(e->e);
+		free(e);
+		e = next;
+	}
+}
+
+
+/* ----- Parser creation --------------------------------------------------- */
+
+
+struct sexpr_ctx *sexpr_new(void)
+{
+	struct sexpr_ctx *ctx;
+
+	ctx = alloc_type(struct sexpr_ctx);
+	ctx->state = idle;
+	ctx->e = NULL;
+	ctx->p = NULL;
+	ctx->sp = &ctx->stack;
+	ctx->stack.next = &ctx->e;
+	ctx->stack.prev = NULL;
+	return ctx;
+}
+
+
+/* ----- Termination ------------------------------------------------------- */
+
+
+bool sexpr_finish(struct sexpr_ctx *ctx, struct expr **res)
+{
+	if (ctx->sp != &ctx->stack) {
+		error("not enough )\n");
+		ctx->state = failed;
+		free_stack(ctx);
+	}
+	if (ctx->state != idle && ctx->state != failed)
+		error("invalid end state %d\n", ctx->state);
+	if (ctx->state == idle) {
+		if (res)
+			*res = ctx->e;
+		else
+			free_expr(ctx->e);
+		free(ctx);
+		return 1;
+	}
+	free_expr(ctx->e);
+	free(ctx);
+	return 0;
+}

eeshow/kicad/sexpr.h

@@ -0,0 +1,47 @@
+/*
+ * kicad/sexpr.h - S-expression parser
+ *
+ * Written 2016 by Werner Almesberger
+ * Copyright 2016 by Werner Almesberger
+ *
+ * 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
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#ifndef KICAD_SEXPR_H
+#define	KICAD_SEXPR_H
+
+#include <stdbool.h>
+
+
+/*
+ * Expression type:
+ *
+ * s		e		Meaning
+ * ------------	--------	----------
+ * NULL		NULL		"" or ()
+ * non-NULL	NULL		foo or "foo"
+ * NULL		non-NULL	(...)
+ * non-NULL	non-NULL	trouble
+ */
+
+struct expr {
+	char *s;		/* string or NULL */
+	struct expr *e;		/* sub-sexpr or NULL*/
+	struct expr *next;
+};
+
+struct sexpr_ctx;
+
+
+void dump_expr(const struct expr *e);
+void free_expr(struct expr *e);
+
+struct sexpr_ctx *sexpr_new(void);
+bool sexpr_parse(struct sexpr_ctx *ctx, const char *s);
+bool sexpr_finish(struct sexpr_ctx *ctx, struct expr **res);
+
+#endif /* !KICAD_SEXPR_H */