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-rw-r--r--json.c558
1 files changed, 558 insertions, 0 deletions
diff --git a/json.c b/json.c
new file mode 100644
index 0000000..f514b4f
--- /dev/null
+++ b/json.c
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+// JSON parser for LSP
+// provides FAST(ish) parsing but SLOW lookup
+// this is especially fast for small objects
+
+typedef struct {
+ u32 pos;
+ u32 len;
+} JSONString;
+
+typedef struct JSONValue JSONValue;
+
+typedef struct {
+ u32 len;
+ // this is an index into the values array
+ // values[items..items+len] store the names
+ // values[items+len..items+2*len] store the values
+ u32 items;
+} JSONObject;
+
+typedef struct {
+ u32 len;
+ // this is an index into the values array
+ // values[elements..elements+len] are the elements
+ u32 elements;
+} JSONArray;
+
+enum {
+ // note: json doesn't actually include undefined.
+ // this is only for returning things from json_get etc.
+ JSON_UNDEFINED,
+ JSON_NULL,
+ JSON_FALSE,
+ JSON_TRUE,
+ JSON_NUMBER,
+ JSON_STRING,
+ JSON_OBJECT,
+ JSON_ARRAY
+};
+
+struct JSONValue {
+ u8 type;
+ union {
+ double number;
+ JSONString string;
+ JSONArray array;
+ JSONObject object;
+ } val;
+};
+
+
+typedef struct {
+ char error[64];
+ const char *text;
+ // root = values[0]
+ JSONValue *values;
+} JSON;
+
+#define SKIP_WHITESPACE while (json_is_space(text[index])) ++index;
+
+
+static bool json_parse_value(JSON *json, u32 *p_index, JSONValue *val);
+
+// defining this instead of using isspace seems to be faster
+// probably because isspace depends on the locale.
+static inline bool json_is_space(char c) {
+ return c == ' ' || c == '\n' || c == '\r' || c == '\t';
+}
+
+static void json_debug_print_value(const JSON *json, const JSONValue *value) {
+ switch (value->type) {
+ case JSON_UNDEFINED: printf("undefined"); break;
+ case JSON_NULL: printf("null"); break;
+ case JSON_FALSE: printf("false"); break;
+ case JSON_TRUE: printf("true"); break;
+ case JSON_NUMBER: printf("%g", value->val.number); break;
+ case JSON_STRING: {
+ const JSONString *string = &value->val.string;
+ printf("\"%.*s\"",
+ (int)string->len,
+ json->text + string->pos);
+ } break;
+ case JSON_ARRAY: {
+ const JSONArray *array = &value->val.array;
+ printf("[");
+ for (u32 i = 0; i < array->len; ++i) {
+ json_debug_print_value(json, &json->values[array->elements + i]);
+ printf(", ");
+ }
+ printf("]");
+ } break;
+ case JSON_OBJECT: {
+ const JSONObject *obj = &value->val.object;
+ printf("{");
+ for (u32 i = 0; i < obj->len; ++i) {
+ json_debug_print_value(json, &json->values[obj->items + i]);
+ printf(": ");
+ json_debug_print_value(json, &json->values[obj->items + obj->len + i]);
+ printf(", ");
+ }
+ printf("}");
+ } break;
+ }
+}
+
+// count number of comma-separated values until
+// closing ] or }
+static u32 json_count(JSON *json, u32 index) {
+ int bracket_depth = 0;
+ int brace_depth = 0;
+ u32 count = 1;
+ const char *text = json->text;
+ SKIP_WHITESPACE;
+ // special case: empty object/array
+ if (text[index] == '}' || text[index] == ']')
+ return 0;
+
+// int mark[5000] = {0};
+ for (; ; ++index) {
+ switch (text[index]) {
+ case '\0':
+ return 0; // bad no closing bracket
+ case '[':
+ ++bracket_depth;
+ break;
+ case ']':
+ --bracket_depth;
+ if (bracket_depth < 0)
+ return count;
+ break;
+ case '{':
+ ++brace_depth;
+// mark[index] = 1;
+ break;
+ case '}':
+ --brace_depth;
+// mark[index] = 1;
+ if (brace_depth < 0){
+ // useful visualization for debugging
+// for (int i = 0; text[i]; ++i ){
+// switch (mark[i]){
+// case 1: printf("\x1b[91m"); break;
+// case 2: printf("\x1b[92m"); break;
+// }
+// printf("%c",text[i]);
+// if (mark[i]) printf("\x1b[0m");
+// }
+// printf("\n");
+
+ return count;
+ }
+ break;
+ case ',':
+ if (bracket_depth == 0 && brace_depth == 0)
+ ++count;
+ break;
+ case '"': {
+ ++index; // skip opening "
+ int escaped = 0;
+ for (; ; ++index) {
+// mark[index] = 2;
+ switch (text[index]) {
+ case '\0': return 0; // bad no closing quote
+ case '\\': escaped = !escaped; break;
+ case '"':
+ if (!escaped)
+ goto done;
+ escaped = false;
+ break;
+ default:
+ escaped = false;
+ break;
+ }
+ }
+ done:;
+ } break;
+ }
+ }
+}
+
+static bool json_parse_object(JSON *json, u32 *p_index, JSONObject *object) {
+ u32 index = *p_index;
+ const char *text = json->text;
+ ++index; // go past {
+ u32 count = json_count(json, index);
+ object->len = count;
+ object->items = arr_len(json->values);
+ arr_set_len(json->values, arr_len(json->values) + 2 * count);
+
+ for (u32 i = 0; i < count; ++i) {
+ if (i > 0) {
+ if (text[index] != ',') {
+ strbuf_printf(json->error, "stuff after value in object");
+ return false;
+ }
+ ++index;
+ }
+ SKIP_WHITESPACE;
+ JSONValue name = {0}, value = {0};
+ if (!json_parse_value(json, &index, &name))
+ return false;
+ SKIP_WHITESPACE;
+ if (text[index] != ':') {
+ strbuf_printf(json->error, "stuff after name in object");
+ return false;
+ }
+ ++index; // skip :
+ SKIP_WHITESPACE;
+ if (!json_parse_value(json, &index, &value))
+ return false;
+ SKIP_WHITESPACE;
+ json->values[object->items + i] = name;
+ json->values[object->items + count + i] = value;
+ }
+
+ if (text[index] != '}') {
+ strbuf_printf(json->error, "mismatched brackets or quotes.");
+ return false;
+ }
+ ++index; // skip }
+ *p_index = index;
+ return true;
+}
+
+static bool json_parse_array(JSON *json, u32 *p_index, JSONArray *array) {
+ u32 index = *p_index;
+ const char *text = json->text;
+ ++index; // go past [
+ u32 count = json_count(json, index);
+ array->len = count;
+ array->elements = arr_len(json->values);
+
+ arr_set_len(json->values, arr_len(json->values) + count);
+
+ SKIP_WHITESPACE;
+
+ for (u32 i = 0; i < count; ++i) {
+ if (i > 0) {
+ if (text[index] != ',') {
+ strbuf_printf(json->error, "stuff after element in array");
+ return false;
+ }
+ ++index;
+ }
+ SKIP_WHITESPACE;
+ JSONValue element = {0};
+ if (!json_parse_value(json, &index, &element))
+ return false;
+ SKIP_WHITESPACE;
+ json->values[array->elements + i] = element;
+ }
+
+ if (text[index] != ']') {
+ strbuf_printf(json->error, "mismatched brackets or quotes.");
+ return false;
+ }
+ ++index; // skip ]
+ *p_index = index;
+ return true;
+}
+
+static bool json_parse_string(JSON *json, u32 *p_index, JSONString *string) {
+ u32 index = *p_index;
+ ++index; // skip opening "
+ string->pos = index;
+ const char *text = json->text;
+ bool escaped = false;
+ for (; ; ++index) {
+ switch (text[index]) {
+ case '"':
+ if (!escaped)
+ goto done;
+ escaped = false;
+ break;
+ case '\\':
+ escaped = !escaped;
+ break;
+ case '\0':
+ strbuf_printf(json->error, "string literal goes to end of JSON");
+ return false;
+ default:
+ escaped = false;
+ break;
+ }
+ }
+ done:
+ string->len = index - string->pos;
+ ++index; // skip closing "
+ *p_index = index;
+ return true;
+}
+
+static bool json_parse_number(JSON *json, u32 *p_index, double *number) {
+ char *endp = NULL;
+ const char *text = json->text;
+ u32 index = *p_index;
+ *number = strtod(text + index, &endp);
+ if (endp == text + index) {
+ strbuf_printf(json->error, "bad number");
+ return false;
+ }
+ index = (u32)(endp - text);
+ *p_index = index;
+ return true;
+}
+
+static bool json_parse_value(JSON *json, u32 *p_index, JSONValue *val) {
+ const char *text = json->text;
+ u32 index = *p_index;
+ SKIP_WHITESPACE;
+ switch (text[index]) {
+ case '{':
+ val->type = JSON_OBJECT;
+ if (!json_parse_object(json, &index, &val->val.object))
+ return false;
+ break;
+ case '[':
+ val->type = JSON_ARRAY;
+ if (!json_parse_array(json, &index, &val->val.array))
+ return false;
+ break;
+ case '"':
+ val->type = JSON_STRING;
+ if (!json_parse_string(json, &index, &val->val.string))
+ return false;
+ break;
+ case ANY_DIGIT:
+ val->type = JSON_NUMBER;
+ if (!json_parse_number(json, &index, &val->val.number))
+ return false;
+ break;
+ case 'f':
+ val->type = JSON_FALSE;
+ if (!str_has_prefix(&text[index], "false"))
+ return false;
+ index += 5;
+ break;
+ case 't':
+ val->type = JSON_TRUE;
+ if (!str_has_prefix(&text[index], "true"))
+ return false;
+ index += 4;
+ break;
+ case 'n':
+ val->type = JSON_NULL;
+ if (!str_has_prefix(&text[index], "null"))
+ return false;
+ index += 4;
+ break;
+ default:
+ strbuf_printf(json->error, "bad value");
+ return false;
+ }
+ *p_index = index;
+ return true;
+}
+
+// NOTE: text must live as long as json!!!
+static bool json_parse(JSON *json, const char *text) {
+ memset(json, 0, sizeof *json);
+ json->text = text;
+ arr_reserve(json->values, strlen(text) / 8);
+ arr_addp(json->values); // add root
+ JSONValue val = {0};
+ u32 index = 0;
+ if (!json_parse_value(json, &index, &val))
+ return false;
+
+ SKIP_WHITESPACE;
+ if (text[index]) {
+ strbuf_printf(json->error, "extra text after end of root object");
+ return false;
+ }
+ json->values[0] = val;
+ return true;
+}
+
+static void json_free(JSON *json) {
+ arr_free(json->values);
+ memset(json, 0, sizeof *json);
+}
+
+static bool json_streq(const JSON *json, const JSONString *string, const char *name) {
+ const char *p = &json->text[string->pos];
+ const char *end = p + string->len;
+ for (; p < end; ++p, ++name) {
+ if (*name != *p)
+ return false;
+ }
+ return *name == '\0';
+}
+
+// returns undefined if the property `name` does not exist.
+static JSONValue json_object_get(const JSON *json, const JSONObject *object, const char *name) {
+ const JSONValue *items = &json->values[object->items];
+ for (u32 i = 0; i < object->len; ++i) {
+ const JSONValue *this_name = items++;
+ if (this_name->type == JSON_STRING && json_streq(json, &this_name->val.string, name)) {
+ return json->values[object->items + object->len + i];
+ }
+ }
+ return (JSONValue){0};
+}
+
+// e.g. if json is { "a" : { "b": 3 }}, then json_get(json, "a.b") = 3.
+// returns undefined if there is no such property
+static JSONValue json_get(const JSON *json, const char *path) {
+ char segment[128];
+ const char *p = path;
+ if (!json->values) {
+ return (JSONValue){0};
+ }
+ JSONValue curr_value = json->values[0];
+ while (*p) {
+ size_t segment_len = strcspn(p, ".");
+ strn_cpy(segment, sizeof segment, p, segment_len);
+ if (curr_value.type != JSON_OBJECT) {
+ return (JSONValue){0};
+ }
+ curr_value = json_object_get(json, &curr_value.val.object, segment);
+ p += segment_len;
+ if (*p == '.') ++p;
+ }
+ return curr_value;
+}
+
+// turn a json string into a null terminated string.
+// this won't be nice if the json string includes \u0000 but that's rare.
+// if buf_sz > string->len, the string will fit.
+static void json_string_get(const JSON *json, const JSONString *string, char *buf, size_t buf_sz) {
+ const char *text = json->text;
+ if (buf_sz == 0) {
+ assert(0);
+ return;
+ }
+ char *buf_end = buf + buf_sz - 1;
+ for (u32 i = string->pos, end = string->pos + string->len; i < end && buf < buf_end; ++i) {
+ if (text[i] != '\\') {
+ *buf++ = text[i];
+ } else {
+ ++i;
+ if (i >= end) break;
+ // escape sequence
+ switch (text[i]) {
+ case 'n': *buf++ = '\n'; break;
+ case 'r': *buf++ = '\r'; break;
+ case 'b': *buf++ = '\b'; break;
+ case 't': *buf++ = '\t'; break;
+ case 'f': *buf++ = '\f'; break;
+ case '\\': *buf++ = '\\'; break;
+ case '/': *buf++ = '/'; break;
+ case '"': *buf++ = '"'; break;
+ case 'u': {
+ if ((buf_end - buf) < 4 || i + 5 > end)
+ goto brk;
+ ++i;
+
+ char hex[5] = {0};
+ hex[0] = text[i++];
+ hex[1] = text[i++];
+ hex[2] = text[i++];
+ hex[3] = text[i++];
+ unsigned code_point=0;
+ sscanf(hex, "%04x", &code_point);
+ // technically this won't deal with people writing out UTF-16 surrogate halves
+ // using \u. i dont care.
+ size_t n = unicode_utf32_to_utf8(buf, code_point);
+ if (n <= 4) buf += n;
+ } break;
+ }
+ }
+ }
+ brk:
+ *buf = '\0';
+}
+
+
+#if __unix__
+static void json_test_time_large(const char *filename) {
+ struct timespec start={0},end={0};
+ FILE *fp = fopen(filename,"rb");
+ if (!fp) {
+ perror(filename);
+ return;
+ }
+
+ fseek(fp,0,SEEK_END);
+ size_t sz = (size_t)ftell(fp);
+ char *buf = calloc(1,sz+1);
+ rewind(fp);
+ fread(buf, 1, sz, fp);
+ fclose(fp);
+ for (int trial = 0; trial < 5; ++trial) {
+ clock_gettime(CLOCK_MONOTONIC, &start);
+ JSON json={0};
+ bool success = json_parse(&json, buf);
+ if (!success) {
+ printf("FAIL: %s\n",json.error);
+ return;
+ }
+
+ json_free(&json);
+ clock_gettime(CLOCK_MONOTONIC, &end);
+
+
+
+ printf("time: %.1fms\n",
+ ((double)end.tv_sec*1e3+(double)end.tv_nsec*1e-6)
+ -((double)start.tv_sec*1e3+(double)start.tv_nsec*1e-6));
+ }
+
+}
+static void json_test_time_small(void) {
+ struct timespec start={0},end={0};
+ int trials = 50000000;
+ clock_gettime(CLOCK_MONOTONIC, &start);
+ for (int trial = 0; trial < trials; ++trial) {
+ JSON json={0};
+ bool success = json_parse(&json, "{\"hello\":\"there\"}");
+ if (!success) {
+ printf("FAIL: %s\n",json.error);
+ return;
+ }
+
+ json_free(&json);
+ }
+ clock_gettime(CLOCK_MONOTONIC, &end);
+ printf("time per trial: %.1fns\n",
+ (((double)end.tv_sec*1e9+(double)end.tv_nsec)
+ -((double)start.tv_sec*1e9+(double)start.tv_nsec))
+ / trials);
+
+}
+#endif
+
+static void json_debug_print(const JSON *json) {
+ printf("%u values (capacity %u, text length %zu)\n",
+ arr_len(json->values), arr_cap(json->values), strlen(json->text));
+ json_debug_print_value(json, &json->values[0]);
+}
+
+// e.g. converts "Hello\nworld" to "Hello\\nworld"
+// the return value is the # of bytes in the escaped string.
+static size_t json_escape_to(char *out, size_t out_sz, const char *in) {
+ (void)out;(void)out_sz;(void)in;
+ // @TODO
+ abort();
+}
+
+// e.g. converts "Hello\nworld" to "Hello\\nworld"
+// the resulting string should be free'd.
+static char *json_escape(const char *str) {
+ size_t out_sz = 2 * strlen(str) + 1;
+ char *out = calloc(1, out_sz);
+ json_escape_to(out, out_sz, str);
+ return out;
+}
+
+#undef SKIP_WHITESPACE
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