tokenizer: new library replacing buffer2array()

The new code is more robust and more flexible.  It provides detailed
error information in GError objects.

Makefile.am

@@ -153,6 +153,7 @@ mpd_headers = \
 	src/tag_id3.h \
 	src/tag_print.h \
 	src/tag_save.h \
+	src/tokenizer.h \
 	src/strset.h \
 	src/uri.h \
 	src/utils.h \
@@ -249,6 +250,7 @@ src_mpd_SOURCES = \
 	src/tag_pool.c \
 	src/tag_print.c \
 	src/tag_save.c \
+	src/tokenizer.c \
 	src/strset.c \
 	src/uri.c \
 	src/utils.c \

src/tokenizer.c

@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "tokenizer.h"
+
+#include <stdbool.h>
+#include <assert.h>
+#include <string.h>
+
+G_GNUC_CONST
+static GQuark
+tokenizer_quark(void)
+{
+	return g_quark_from_static_string("tokenizer");
+}
+
+static inline bool
+valid_word_first_char(char ch)
+{
+	return g_ascii_isalpha(ch);
+}
+
+static inline bool
+valid_word_char(char ch)
+{
+	return g_ascii_isalnum(ch) || ch == '_';
+}
+
+char *
+tokenizer_next_word(char **input_p, GError **error_r)
+{
+	char *word, *input;
+
+	assert(input_p != NULL);
+	assert(*input_p != NULL);
+
+	word = input = *input_p;
+
+	if (*input == 0)
+		return NULL;
+
+	/* check the first character */
+
+	if (!valid_word_first_char(*input)) {
+		g_set_error(error_r, tokenizer_quark(), 0,
+			    "Letter expected");
+		return NULL;
+	}
+
+	/* now iterate over the other characters until we find a
+	   whitespace or end-of-string */
+
+	while (*++input != 0) {
+		if (g_ascii_isspace(*input)) {
+			/* a whitespace: the word ends here */
+			*input = 0;
+			/* skip all following spaces, too */
+			input = g_strchug(input + 1);
+			break;
+		}
+
+		if (!valid_word_char(*input)) {
+			*input_p = input;
+			g_set_error(error_r, tokenizer_quark(), 0,
+				    "Invalid word character");
+			return NULL;
+		}
+	}
+
+	/* end of string: the string is already null-terminated
+	   here */
+
+	*input_p = input;
+	return word;
+}
+
+char *
+tokenizer_next_string(char **input_p, GError **error_r)
+{
+	char *word, *dest, *input;
+
+	assert(input_p != NULL);
+	assert(*input_p != NULL);
+
+	word = dest = input = *input_p;
+
+	if (*input == 0)
+		/* end of line */
+		return NULL;
+
+	/* check for the opening " */
+
+	if (*input != '"') {
+		g_set_error(error_r, tokenizer_quark(), 0,
+			    "'\"' expected");
+		return NULL;
+	}
+
+	++input;
+
+	/* copy all characters */
+
+	while (*input != '"') {
+		if (*input == '\\')
+			/* the backslash escapes the following
+			   character */
+			++input;
+
+		if (*input == 0) {
+			/* return input-1 so the caller can see the
+			   difference between "end of line" and
+			   "error" */
+			*input_p = input - 1;
+			g_set_error(error_r, tokenizer_quark(), 0,
+				    "Missing closing '\"'");
+			return NULL;
+		}
+
+		/* copy one character */
+		*dest++ = *input++;
+	}
+
+	/* the following character must be a whitespace (or end of
+	   line) */
+
+	++input;
+	if (*input != 0 && !g_ascii_isspace(*input)) {
+		*input_p = input;
+		g_set_error(error_r, tokenizer_quark(), 0,
+			    "Space expected after closing '\"'");
+		return NULL;
+	}
+
+	/* finish the string and return it */
+
+	*dest = 0;
+	*input_p = g_strchug(input);
+	return word;
+}
+
+char *
+tokenizer_next_word_or_string(char **input_p, GError **error_r)
+{
+	assert(input_p != NULL);
+	assert(*input_p != NULL);
+
+	if (**input_p == '"')
+		return tokenizer_next_string(input_p, error_r);
+	else
+		return tokenizer_next_word(input_p, error_r);
+}

src/tokenizer.h

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_TOKENIZER_H
+#define MPD_TOKENIZER_H
+
+#include <glib.h>
+
+/**
+ * Reads the next word from the input string.  This function modifies
+ * the input string.
+ *
+ * @param input_p the input string; this function returns a pointer to
+ * the first non-whitespace character of the following token
+ * @param error_r if this function returns NULL and **input_p!=0, it
+ * optionally provides a GError object in this argument
+ * @return a pointer to the null-terminated word, or NULL on error or
+ * end of line
+ */
+char *
+tokenizer_next_word(char **input_p, GError **error_r);
+
+/**
+ * Reads the next quoted string from the input string.  A backslash
+ * escapes the following character.  This function modifies the input
+ * string.
+ *
+ * @param input_p the input string; this function returns a pointer to
+ * the first non-whitespace character of the following token
+ * @param error_r if this function returns NULL and **input_p!=0, it
+ * optionally provides a GError object in this argument
+ * @return a pointer to the null-terminated string, or NULL on error
+ * or end of line
+ */
+char *
+tokenizer_next_string(char **input_p, GError **error_r);
+
+/**
+ * Reads the next word or quoted string from the input.  This is a
+ * wrapper for tokenizer_next_word() and tokenizer_next_string().
+ *
+ * @param input_p the input string; this function returns a pointer to
+ * the first non-whitespace character of the following token
+ * @param error_r if this function returns NULL and **input_p!=0, it
+ * optionally provides a GError object in this argument
+ * @return a pointer to the null-terminated string, or NULL on error
+ * or end of line
+ */
+char *
+tokenizer_next_word_or_string(char **input_p, GError **error_r);
+
+#endif