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authorAnthony Liguori <aliguori@us.ibm.com>2009-11-11 10:39:23 -0600
committerAnthony Liguori <aliguori@us.ibm.com>2009-11-17 08:49:39 -0600
commit4a5fcab7acc55495d0a617eeebbbeaebc1872dbf (patch)
treed9af15127fa09c0498948ef7e96440fa53ead113 /json-parser.c
parentd7ff3acbb4496ecae92d7ce1d52579d55b19da2f (diff)
Add a JSON parser
This is the third and final stage of the JSON parser. It parses lexical tokens performing grammar validation and creating the final QObject representation. It uses a recursive decent parser. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'json-parser.c')
-rw-r--r--json-parser.c568
1 files changed, 568 insertions, 0 deletions
diff --git a/json-parser.c b/json-parser.c
new file mode 100644
index 000000000..7624c0f9b
--- /dev/null
+++ b/json-parser.c
@@ -0,0 +1,568 @@
+/*
+ * JSON Parser
+ *
+ * Copyright IBM, Corp. 2009
+ *
+ * Authors:
+ * Anthony Liguori <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include <stdbool.h>
+
+#include "qemu-common.h"
+#include "qstring.h"
+#include "qint.h"
+#include "qdict.h"
+#include "qlist.h"
+#include "qfloat.h"
+#include "qbool.h"
+#include "json-parser.h"
+#include "json-lexer.h"
+
+typedef struct JSONParserContext
+{
+} JSONParserContext;
+
+#define BUG_ON(cond) assert(!(cond))
+
+/**
+ * TODO
+ *
+ * 0) make errors meaningful again
+ * 1) add geometry information to tokens
+ * 3) should we return a parsed size?
+ * 4) deal with premature EOI
+ */
+
+static QObject *parse_value(JSONParserContext *ctxt, QList **tokens, va_list *ap);
+
+/**
+ * Token manipulators
+ *
+ * tokens are dictionaries that contain a type, a string value, and geometry information
+ * about a token identified by the lexer. These are routines that make working with
+ * these objects a bit easier.
+ */
+static const char *token_get_value(QObject *obj)
+{
+ return qdict_get_str(qobject_to_qdict(obj), "token");
+}
+
+static JSONTokenType token_get_type(QObject *obj)
+{
+ return qdict_get_int(qobject_to_qdict(obj), "type");
+}
+
+static int token_is_operator(QObject *obj, char op)
+{
+ const char *val;
+
+ if (token_get_type(obj) != JSON_OPERATOR) {
+ return 0;
+ }
+
+ val = token_get_value(obj);
+
+ return (val[0] == op) && (val[1] == 0);
+}
+
+static int token_is_keyword(QObject *obj, const char *value)
+{
+ if (token_get_type(obj) != JSON_KEYWORD) {
+ return 0;
+ }
+
+ return strcmp(token_get_value(obj), value) == 0;
+}
+
+static int token_is_escape(QObject *obj, const char *value)
+{
+ if (token_get_type(obj) != JSON_ESCAPE) {
+ return 0;
+ }
+
+ return (strcmp(token_get_value(obj), value) == 0);
+}
+
+/**
+ * Error handler
+ */
+static void parse_error(JSONParserContext *ctxt, QObject *token, const char *msg, ...)
+{
+ fprintf(stderr, "parse error: %s\n", msg);
+}
+
+/**
+ * String helpers
+ *
+ * These helpers are used to unescape strings.
+ */
+static void wchar_to_utf8(uint16_t wchar, char *buffer, size_t buffer_length)
+{
+ if (wchar <= 0x007F) {
+ BUG_ON(buffer_length < 2);
+
+ buffer[0] = wchar & 0x7F;
+ buffer[1] = 0;
+ } else if (wchar <= 0x07FF) {
+ BUG_ON(buffer_length < 3);
+
+ buffer[0] = 0xC0 | ((wchar >> 6) & 0x1F);
+ buffer[1] = 0x80 | (wchar & 0x3F);
+ buffer[2] = 0;
+ } else {
+ BUG_ON(buffer_length < 4);
+
+ buffer[0] = 0xE0 | ((wchar >> 12) & 0x0F);
+ buffer[1] = 0x80 | ((wchar >> 6) & 0x3F);
+ buffer[2] = 0x80 | (wchar & 0x3F);
+ buffer[3] = 0;
+ }
+}
+
+static int hex2decimal(char ch)
+{
+ if (ch >= '0' && ch <= '9') {
+ return (ch - '0');
+ } else if (ch >= 'a' && ch <= 'f') {
+ return 10 + (ch - 'a');
+ } else if (ch >= 'A' && ch <= 'F') {
+ return 10 + (ch - 'A');
+ }
+
+ return -1;
+}
+
+/**
+ * parse_string(): Parse a json string and return a QObject
+ *
+ * string
+ * ""
+ * " chars "
+ * chars
+ * char
+ * char chars
+ * char
+ * any-Unicode-character-
+ * except-"-or-\-or-
+ * control-character
+ * \"
+ * \\
+ * \/
+ * \b
+ * \f
+ * \n
+ * \r
+ * \t
+ * \u four-hex-digits
+ */
+static QString *qstring_from_escaped_str(JSONParserContext *ctxt, QObject *token)
+{
+ const char *ptr = token_get_value(token);
+ QString *str;
+ int double_quote = 1;
+
+ if (*ptr == '"') {
+ double_quote = 1;
+ } else {
+ double_quote = 0;
+ }
+ ptr++;
+
+ str = qstring_new();
+ while (*ptr &&
+ ((double_quote && *ptr != '"') || (!double_quote && *ptr != '\''))) {
+ if (*ptr == '\\') {
+ ptr++;
+
+ switch (*ptr) {
+ case '"':
+ qstring_append(str, "\"");
+ ptr++;
+ break;
+ case '\'':
+ qstring_append(str, "'");
+ ptr++;
+ break;
+ case '\\':
+ qstring_append(str, "\\");
+ ptr++;
+ break;
+ case '/':
+ qstring_append(str, "/");
+ ptr++;
+ break;
+ case 'b':
+ qstring_append(str, "\b");
+ ptr++;
+ break;
+ case 'n':
+ qstring_append(str, "\n");
+ ptr++;
+ break;
+ case 'r':
+ qstring_append(str, "\r");
+ ptr++;
+ break;
+ case 't':
+ qstring_append(str, "\t");
+ ptr++;
+ break;
+ case 'u': {
+ uint16_t unicode_char = 0;
+ char utf8_char[4];
+ int i = 0;
+
+ ptr++;
+
+ for (i = 0; i < 4; i++) {
+ if (qemu_isxdigit(*ptr)) {
+ unicode_char |= hex2decimal(*ptr) << ((3 - i) * 4);
+ } else {
+ parse_error(ctxt, token,
+ "invalid hex escape sequence in string");
+ goto out;
+ }
+ ptr++;
+ }
+
+ wchar_to_utf8(unicode_char, utf8_char, sizeof(utf8_char));
+ qstring_append(str, utf8_char);
+ } break;
+ default:
+ parse_error(ctxt, token, "invalid escape sequence in string");
+ goto out;
+ }
+ } else {
+ char dummy[2];
+
+ dummy[0] = *ptr++;
+ dummy[1] = 0;
+
+ qstring_append(str, dummy);
+ }
+ }
+
+ ptr++;
+
+ return str;
+
+out:
+ QDECREF(str);
+ return NULL;
+}
+
+/**
+ * Parsing rules
+ */
+static int parse_pair(JSONParserContext *ctxt, QDict *dict, QList **tokens, va_list *ap)
+{
+ QObject *key, *token = NULL, *value, *peek;
+ QList *working = qlist_copy(*tokens);
+
+ peek = qlist_peek(working);
+ key = parse_value(ctxt, &working, ap);
+ if (qobject_type(key) != QTYPE_QSTRING) {
+ parse_error(ctxt, peek, "key is not a string in object");
+ goto out;
+ }
+
+ token = qlist_pop(working);
+ if (!token_is_operator(token, ':')) {
+ parse_error(ctxt, token, "missing : in object pair");
+ goto out;
+ }
+
+ value = parse_value(ctxt, &working, ap);
+ if (value == NULL) {
+ parse_error(ctxt, token, "Missing value in dict");
+ goto out;
+ }
+
+ qdict_put_obj(dict, qstring_get_str(qobject_to_qstring(key)), value);
+
+ qobject_decref(token);
+ qobject_decref(key);
+ QDECREF(*tokens);
+ *tokens = working;
+
+ return 0;
+
+out:
+ qobject_decref(token);
+ qobject_decref(key);
+ QDECREF(working);
+
+ return -1;
+}
+
+static QObject *parse_object(JSONParserContext *ctxt, QList **tokens, va_list *ap)
+{
+ QDict *dict = NULL;
+ QObject *token, *peek;
+ QList *working = qlist_copy(*tokens);
+
+ token = qlist_pop(working);
+ if (!token_is_operator(token, '{')) {
+ goto out;
+ }
+ qobject_decref(token);
+ token = NULL;
+
+ dict = qdict_new();
+
+ peek = qlist_peek(working);
+ if (!token_is_operator(peek, '}')) {
+ if (parse_pair(ctxt, dict, &working, ap) == -1) {
+ goto out;
+ }
+
+ token = qlist_pop(working);
+ while (!token_is_operator(token, '}')) {
+ if (!token_is_operator(token, ',')) {
+ parse_error(ctxt, token, "expected separator in dict");
+ goto out;
+ }
+ qobject_decref(token);
+ token = NULL;
+
+ if (parse_pair(ctxt, dict, &working, ap) == -1) {
+ goto out;
+ }
+
+ token = qlist_pop(working);
+ }
+ qobject_decref(token);
+ token = NULL;
+ } else {
+ token = qlist_pop(working);
+ qobject_decref(token);
+ token = NULL;
+ }
+
+ QDECREF(*tokens);
+ *tokens = working;
+
+ return QOBJECT(dict);
+
+out:
+ qobject_decref(token);
+ QDECREF(working);
+ QDECREF(dict);
+ return NULL;
+}
+
+static QObject *parse_array(JSONParserContext *ctxt, QList **tokens, va_list *ap)
+{
+ QList *list = NULL;
+ QObject *token, *peek;
+ QList *working = qlist_copy(*tokens);
+
+ token = qlist_pop(working);
+ if (!token_is_operator(token, '[')) {
+ goto out;
+ }
+ qobject_decref(token);
+ token = NULL;
+
+ list = qlist_new();
+
+ peek = qlist_peek(working);
+ if (!token_is_operator(peek, ']')) {
+ QObject *obj;
+
+ obj = parse_value(ctxt, &working, ap);
+ if (obj == NULL) {
+ parse_error(ctxt, token, "expecting value");
+ goto out;
+ }
+
+ qlist_append_obj(list, obj);
+
+ token = qlist_pop(working);
+ while (!token_is_operator(token, ']')) {
+ if (!token_is_operator(token, ',')) {
+ parse_error(ctxt, token, "expected separator in list");
+ goto out;
+ }
+
+ qobject_decref(token);
+ token = NULL;
+
+ obj = parse_value(ctxt, &working, ap);
+ if (obj == NULL) {
+ parse_error(ctxt, token, "expecting value");
+ goto out;
+ }
+
+ qlist_append_obj(list, obj);
+
+ token = qlist_pop(working);
+ }
+
+ qobject_decref(token);
+ token = NULL;
+ } else {
+ token = qlist_pop(working);
+ qobject_decref(token);
+ token = NULL;
+ }
+
+ QDECREF(*tokens);
+ *tokens = working;
+
+ return QOBJECT(list);
+
+out:
+ qobject_decref(token);
+ QDECREF(working);
+ QDECREF(list);
+ return NULL;
+}
+
+static QObject *parse_keyword(JSONParserContext *ctxt, QList **tokens)
+{
+ QObject *token, *ret;
+ QList *working = qlist_copy(*tokens);
+
+ token = qlist_pop(working);
+
+ if (token_get_type(token) != JSON_KEYWORD) {
+ goto out;
+ }
+
+ if (token_is_keyword(token, "true")) {
+ ret = QOBJECT(qbool_from_int(true));
+ } else if (token_is_keyword(token, "false")) {
+ ret = QOBJECT(qbool_from_int(false));
+ } else {
+ parse_error(ctxt, token, "invalid keyword `%s'", token_get_value(token));
+ goto out;
+ }
+
+ qobject_decref(token);
+ QDECREF(*tokens);
+ *tokens = working;
+
+ return ret;
+
+out:
+ qobject_decref(token);
+ QDECREF(working);
+
+ return NULL;
+}
+
+static QObject *parse_escape(JSONParserContext *ctxt, QList **tokens, va_list *ap)
+{
+ QObject *token = NULL, *obj;
+ QList *working = qlist_copy(*tokens);
+
+ if (ap == NULL) {
+ goto out;
+ }
+
+ token = qlist_pop(working);
+
+ if (token_is_escape(token, "%p")) {
+ obj = va_arg(*ap, QObject *);
+ } else if (token_is_escape(token, "%i")) {
+ obj = QOBJECT(qbool_from_int(va_arg(*ap, int)));
+ } else if (token_is_escape(token, "%d")) {
+ obj = QOBJECT(qint_from_int(va_arg(*ap, int)));
+ } else if (token_is_escape(token, "%ld")) {
+ obj = QOBJECT(qint_from_int(va_arg(*ap, long)));
+ } else if (token_is_escape(token, "%lld")) {
+ obj = QOBJECT(qint_from_int(va_arg(*ap, long long)));
+ } else if (token_is_escape(token, "%s")) {
+ obj = QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
+ } else if (token_is_escape(token, "%f")) {
+ obj = QOBJECT(qfloat_from_double(va_arg(*ap, double)));
+ } else {
+ goto out;
+ }
+
+ qobject_decref(token);
+ QDECREF(*tokens);
+ *tokens = working;
+
+ return obj;
+
+out:
+ qobject_decref(token);
+ QDECREF(working);
+
+ return NULL;
+}
+
+static QObject *parse_literal(JSONParserContext *ctxt, QList **tokens)
+{
+ QObject *token, *obj;
+ QList *working = qlist_copy(*tokens);
+
+ token = qlist_pop(working);
+ switch (token_get_type(token)) {
+ case JSON_STRING:
+ obj = QOBJECT(qstring_from_escaped_str(ctxt, token));
+ break;
+ case JSON_INTEGER:
+ obj = QOBJECT(qint_from_int(strtoll(token_get_value(token), NULL, 10)));
+ break;
+ case JSON_FLOAT:
+ /* FIXME dependent on locale */
+ obj = QOBJECT(qfloat_from_double(strtod(token_get_value(token), NULL)));
+ break;
+ default:
+ goto out;
+ }
+
+ qobject_decref(token);
+ QDECREF(*tokens);
+ *tokens = working;
+
+ return obj;
+
+out:
+ qobject_decref(token);
+ QDECREF(working);
+
+ return NULL;
+}
+
+static QObject *parse_value(JSONParserContext *ctxt, QList **tokens, va_list *ap)
+{
+ QObject *obj;
+
+ obj = parse_object(ctxt, tokens, ap);
+ if (obj == NULL) {
+ obj = parse_array(ctxt, tokens, ap);
+ }
+ if (obj == NULL) {
+ obj = parse_escape(ctxt, tokens, ap);
+ }
+ if (obj == NULL) {
+ obj = parse_keyword(ctxt, tokens);
+ }
+ if (obj == NULL) {
+ obj = parse_literal(ctxt, tokens);
+ }
+
+ return obj;
+}
+
+QObject *json_parser_parse(QList *tokens, va_list *ap)
+{
+ JSONParserContext ctxt = {};
+ QList *working = qlist_copy(tokens);
+ QObject *result;
+
+ result = parse_value(&ctxt, &working, ap);
+
+ QDECREF(working);
+
+ return result;
+}