Patchwork [08/11] Add a JSON message boundary identifier

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Submitter Anthony Liguori
Date Nov. 11, 2009, 5:29 p.m.
Message ID <1257960543-26373-8-git-send-email-aliguori@us.ibm.com>
Download mbox | patch
Permalink /patch/38156/
State New
Headers show

Comments

Anthony Liguori - Nov. 11, 2009, 5:29 p.m.
The second stage of our JSON parser is a simple state machine that identifies
individual JSON values by counting the levels of nesting of tokens.  It does
not perform grammar validation.  We use this to emit a full JSON value to the
parser.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
 Makefile        |    1 +
 json-streamer.c |   88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 json-streamer.h |   39 ++++++++++++++++++++++++
 3 files changed, 128 insertions(+), 0 deletions(-)
 create mode 100644 json-streamer.c
 create mode 100644 json-streamer.h

Patch

diff --git a/Makefile b/Makefile
index e5ab879..a2aab60 100644
--- a/Makefile
+++ b/Makefile
@@ -136,6 +136,7 @@  obj-y += qemu-char.o aio.o savevm.o
 obj-y += msmouse.o ps2.o
 obj-y += qdev.o qdev-properties.o
 obj-y += qint.o qstring.o qdict.o qlist.o qfloat.o qbool.o json-lexer.o
+obj-y += json-streamer.o
 obj-y += qemu-config.o
 
 obj-$(CONFIG_BRLAPI) += baum.o
diff --git a/json-streamer.c b/json-streamer.c
new file mode 100644
index 0000000..610ffea
--- /dev/null
+++ b/json-streamer.c
@@ -0,0 +1,88 @@ 
+/*
+ * JSON streaming support
+ *
+ * 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 "qlist.h"
+#include "qint.h"
+#include "qdict.h"
+#include "qemu-common.h"
+#include "json-lexer.h"
+#include "json-streamer.h"
+
+static void json_message_process_token(JSONLexer *lexer, QString *token, JSONTokenType type, int x, int y)
+{
+    JSONMessageParser *parser = container_of(lexer, JSONMessageParser, lexer);
+    QDict *dict;
+
+    if (type == JSON_OPERATOR) {
+        switch (qstring_get_str(token)[0]) {
+        case '{':
+            parser->brace_count++;
+            break;
+        case '}':
+            parser->brace_count--;
+            break;
+        case '[':
+            parser->bracket_count++;
+            break;
+        case ']':
+            parser->bracket_count--;
+            break;
+        default:
+            break;
+        }
+    }
+
+    dict = qdict_new();
+    qdict_put_obj(dict, "type", QOBJECT(qint_from_int(type)));
+    QINCREF(token);
+    qdict_put_obj(dict, "token", QOBJECT(token));
+    qdict_put_obj(dict, "x", QOBJECT(qint_from_int(x)));
+    qdict_put_obj(dict, "y", QOBJECT(qint_from_int(y)));
+
+    qlist_append(parser->tokens, dict);
+
+    if (parser->brace_count == 0 &&
+        parser->bracket_count == 0) {
+        parser->emit(parser, parser->tokens);
+        QDECREF(parser->tokens);
+        parser->tokens = qlist_new();
+    }
+}
+
+void json_message_parser_init(JSONMessageParser *parser,
+                              void (*func)(JSONMessageParser *, QList *))
+{
+    parser->emit = func;
+    parser->brace_count = 0;
+    parser->bracket_count = 0;
+    parser->tokens = qlist_new();
+
+    json_lexer_init(&parser->lexer, json_message_process_token);
+}
+
+int json_message_parser_feed(JSONMessageParser *parser,
+                             const char *buffer, size_t size)
+{
+    return json_lexer_feed(&parser->lexer, buffer, size);
+}
+
+int json_message_parser_flush(JSONMessageParser *parser)
+{
+    return json_lexer_flush(&parser->lexer);
+}
+
+void json_message_parser_destroy(JSONMessageParser *parser)
+{
+    json_lexer_destroy(&parser->lexer);
+    QDECREF(parser->tokens);
+}
diff --git a/json-streamer.h b/json-streamer.h
new file mode 100644
index 0000000..09f3bd7
--- /dev/null
+++ b/json-streamer.h
@@ -0,0 +1,39 @@ 
+/*
+ * JSON streaming support
+ *
+ * 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.
+ *
+ */
+
+#ifndef QEMU_JSON_STREAMER_H
+#define QEMU_JSON_STREAMER_H
+
+#include "qlist.h"
+#include "json-lexer.h"
+
+typedef struct JSONMessageParser
+{
+    void (*emit)(struct JSONMessageParser *parser, QList *tokens);
+    JSONLexer lexer;
+    int brace_count;
+    int bracket_count;
+    QList *tokens;
+} JSONMessageParser;
+
+void json_message_parser_init(JSONMessageParser *parser,
+                              void (*func)(JSONMessageParser *, QList *));
+
+int json_message_parser_feed(JSONMessageParser *parser,
+                             const char *buffer, size_t size);
+
+int json_message_parser_flush(JSONMessageParser *parser);
+
+void json_message_parser_destroy(JSONMessageParser *parser);
+
+#endif