From: Heng Li <lh3@me.com>
Date: Sat, 29 Nov 2014 23:20:35 +0000 (-0500)
Subject: added JSON query
X-Git-Url: http://www.kaiwu.me/postgresql/commit/?a=commitdiff_plain;h=d4827d96c44a8c950115b6d23fac1b7037c7fb8b;p=klib.git

added JSON query
---

diff --git a/kson.c b/kson.c
index a962ba7..311780d 100644
--- a/kson.c
+++ b/kson.c
@@ -1,5 +1,6 @@
 #include <string.h>
 #include <stdlib.h>
+#include <stdarg.h>
 #include <ctype.h>
 #include <stdio.h>
 #include "kson.h"
@@ -118,7 +119,7 @@ kson_t *kson_parse(const char *json, int *error)
 	return kson;
 }
 
-void kson_print_recur(kson_node_t *nodes, kson_node_t *p)
+void kson_print_recur(const kson_node_t *nodes, const kson_node_t *p)
 {
 	if (p->key) {
 		printf("\"%s\"", p->key);
@@ -141,11 +142,45 @@ void kson_print_recur(kson_node_t *nodes, kson_node_t *p)
 	}
 }
 
-void kson_print(kson_t *kson)
+void kson_print(const kson_t *kson)
 {
 	kson_print_recur(kson->nodes, kson->nodes);
 }
 
+const kson_node_t *kson_vquery(const kson_node_t *nodes, const kson_node_t *root, int depth, va_list ap)
+{
+	const kson_node_t *p = root;
+	while (p && depth > 0) {
+		if (p->type == KSON_TYPE_BRACE) {
+			long i;
+			const char *q = va_arg(ap, const char*);
+			for (i = 0; i < (long)p->n; ++i) {
+				const kson_node_t *r = &nodes[i];
+				if (r->key && strcmp(r->key, q) == 0) {
+					p = r;
+					break;
+				}
+			}
+			if (i == (long)p->n) p = 0;
+		} else if (p->type == KSON_TYPE_BRACKET) {
+			long i = va_arg(ap, long);
+			p = i < (long)p->n? &nodes[p->v.child[i]] : 0;
+		} else break;
+		--depth;
+	}
+	return p;
+}
+
+const kson_node_t *kson_query(const kson_t *kson, int depth, ...)
+{
+	const kson_node_t *p;
+	va_list ap;
+	va_start(ap, depth);
+	p = kson_vquery(kson->nodes, kson->nodes, depth, ap);
+	va_end(ap);
+	return p;
+}
+
 #ifdef KSON_MAIN
 int main(int argc, char *argv[])
 {
@@ -153,6 +188,8 @@ int main(int argc, char *argv[])
 	int error;
 	kson = kson_parse("{'a' : 1, 'b':[0,'isn\\'t',true],'d':[{\n}]}", &error);
 	if (error == 0) {
+		const kson_node_t *p = kson_query(kson, 2, "b", 1);
+		printf("*** %s\n", p->v.str);
 		kson_print(kson);
 		putchar('\n');
 	} else {
diff --git a/kson.h b/kson.h
index 8b0a1e2..9a44fbc 100644
--- a/kson.h
+++ b/kson.h
@@ -28,27 +28,29 @@ typedef struct {
 	kson_node_t *nodes;
 } kson_t;
 
+#define kson_is_internal(p) ((p)->type == KSON_TYPE_BRACKET || (p)->type == KSON_TYPE_BRACE)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 	/**
-	 * Parse a JSON string into nodes
+	 * Parse a JSON string
 	 *
-	 * @param json        JSON string
-	 * @param n_nodes     number of nodes
-	 * @param error       0 if no error; or set to one of KSON_ERR_* values
-	 * @param parsed_len  if not NULL, equal to the parsed length
+	 * @param json    JSON string
+	 * @param error   error code
 	 *
-	 * @return An array of size $n_nodes keeping parsed nodes
+	 * @return a pointer to kson_t if *error==0; or NULL otherwise
 	 */
-	kson_node_t *kson_parse_core(const char *json, long *n_nodes, int *error, long *parsed_len);
-
-	// Equivalent to: { kson->nodes = kson_parse_core(json, &kson->n_nodes, &error, 0); return *error? 0 : kson; } 
 	kson_t *kson_parse(const char *json, int *error);
 
+	/** Destroy a kson_t object */
 	void kson_destroy(kson_t *kson);
-	void kson_print(kson_t *kson);
+
+	const kson_node_t *kson_query(const kson_t *kson, int max_depth, ...);
+
+	void kson_print(const kson_t *kson);
+	kson_node_t *kson_parse_core(const char *json, long *n_nodes, int *error, long *parsed_len);
 
 #ifdef __cplusplus
 }