From f67e97cd08b838b5ad40449c199ef6210f125d98 Mon Sep 17 00:00:00 2001
From: Eric Fischer <enf@pobox.com>
Date: Thu, 6 Feb 2014 22:45:40 -0800
Subject: [PATCH] Work out more details of how json_free() needs to work.

The idea is that you can free any element once you are
done with it, even if it is part of an array or hash that
isn't completely read yet.

Removing array elements is reasonably well defined because
nothing else depends on them. Removing a hash key or value
causes it to be replaced by a null unless the other side of
the component has already been nulled out, in which case
the whole pair is removed.
---
 jsonpull.c | 65 ++++++++++++++++++++++++++++++++++++++++--------------
 jsonpull.h |  1 +
 2 files changed, 49 insertions(+), 17 deletions(-)

diff --git a/jsonpull.c b/jsonpull.c
index c70285c6..80dc4988 100644
--- a/jsonpull.c
+++ b/jsonpull.c
@@ -459,6 +459,17 @@ again:
 	return NULL;
 }
 
+static json_object *fabricate_null(json_object *parent) {
+	json_object *o = malloc(sizeof(struct json_object));
+	o->type = JSON_NULL;
+	o->parent = parent;
+	o->array = NULL;
+	o->keys = NULL;
+	o->values = NULL;
+	o->length = 0;
+	return o;
+}
+
 void json_free(json_object *o) {
 	int i;
 
@@ -469,14 +480,33 @@ void json_free(json_object *o) {
 	// Free any data linked from here
 
 	if (o->type == JSON_ARRAY) {
-		for (i = 0; i < o->length; i++) {
-			json_free(o->array[i]);
+		json_object **a = o->array;
+		int n = o->length;
+
+		o->array = NULL;
+		o->length = 0;
+
+		for (i = 0; i < n; i++) {
+			json_free(a[i]);
 		}
+
+		free(a);
 	} else if (o->type == JSON_HASH) {
-		for (i = 0; i < o->length; i++) {
-			json_free(o->keys[i]);
-			json_free(o->values[i]);
+		json_object **k = o->keys;
+		json_object **v = o->values;
+		int n = o->length;
+
+		o->keys = NULL;
+		o->values = NULL;
+		o->length = 0;
+
+		for (i = 0; i < n; i++) {
+			json_free(k[i]);
+			json_free(v[i]);
 		}
+
+		free(k);
+		free(v);
 	} else if (o->type == JSON_STRING) {
 		free(o->string);
 	}
@@ -500,24 +530,25 @@ void json_free(json_object *o) {
 
 		if (o->parent->type == JSON_HASH) {
 			for (i = 0; i < o->parent->length; i++) {
-				if (o->parent->keys[i] == o || o->parent->values[i] == o) {
+				if (o->parent->keys[i] == o) {
+					o->parent->keys[i] = fabricate_null(o->parent);
+					break;
+				}
+				if (o->parent->values[i] == o) {
+					o->parent->values[i] = fabricate_null(o->parent);
 					break;
 				}
 			}
 
 			if (i < o->parent->length) {
-				json_object *k = o->parent->keys[i];
-				json_object *v = o->parent->values[i];
+				if (o->parent->keys[i] != NULL && o->parent->keys[i]->type == JSON_NULL) {
+					if (o->parent->values[i] != NULL && o->parent->values[i]->type == JSON_NULL) {
+						free(o->parent->keys[i]);
+						free(o->parent->values[i]);
 
-				memmove(o->parent->keys + i, o->parent->keys + i + 1, o->parent->length - i - 1);
-				memmove(o->parent->values + i, o->parent->values + i + 1, o->parent->length - i - 1);
-				o->parent->length--;
-				
-				if (o->parent->values[i] == NULL) {
-					// Have not yet read the value for this pair
-				} else {
-					if (o->parent->keys[i] == o) {
-					} else {
+						memmove(o->parent->keys + i, o->parent->keys + i + 1, o->parent->length - i - 1);
+						memmove(o->parent->values + i, o->parent->values + i + 1, o->parent->length - i - 1);
+						o->parent->length--;
 					}
 				}
 			}
diff --git a/jsonpull.h b/jsonpull.h
index 6a19f90f..b0633a76 100644
--- a/jsonpull.h
+++ b/jsonpull.h
@@ -33,5 +33,6 @@ typedef struct json_pull json_pull;
 json_pull *json_begin_file(FILE *f);
 json_pull *json_begin_string(char *s);
 json_object *json_parse(json_pull *j);
+void json_free(json_object *j);
 
 json_object *json_hash_get(json_object *o, char *s);