1 files changed, 263 insertions, 0 deletions
diff --git a/src/json.c b/src/json.c
new file mode 100644
index 0000000..6f00da8
--- /dev/null
+++ b/src/json.c
@@ -0,0 +1,263 @@
+#include <assert.h>
+#include <ctype.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "../include/json.h"
+#include "../include/str.h"
+#include "../include/types.h"
+
+JSONObject *JSONObject_new(Arena *a) {
+    JSONObject *object = new(a, JSONObject, 1);
+    object->len = 0;
+    object->keys = Vec_new(a, Str, 2);
+    object->values = Vec_new(a, JSON, 2);
+    return object;
+}
+
+JSON JSON_integer(i32 value) {
+    JSON json = {0};
+    json.type = JSON_INTEGER;
+    json.as.integer = value;
+    return json;
+}
+
+JSON JSON_float(f32 value) {
+    JSON json = {0};
+    json.type = JSON_FLOAT;
+    json.as.floating = value;
+    return json;
+}
+
+JSON JSON_array(Vec items) {
+    JSON json = {0};
+    json.type = JSON_ARRAY;
+    json.as.array = items;
+    return json;
+}
+
+JSON JSON_string(Str value) {
+    JSON json = {0};
+    json.type = JSON_STRING;
+    json.as.string = value;
+    return json;
+}
+
+JSON JSON_object(size len, Vec keys, Vec values) {
+    assert(len == keys.len && len == values.len);
+    JSON json = {0};
+    json.type = JSON_OBJECT;
+    json.as.object.len = len;
+    json.as.object.keys = keys;
+    json.as.object.values = values;
+    return json;
+}
+
+JSON JSON_boolean(bool value) {
+    JSON json = {0};
+    json.type = JSON_BOOL;
+    json.as.boolean = value;
+    return json;
+}
+
+JSON JSON_null() {
+    JSON json = {0};
+    json.type = JSON_NULL;
+    return json;
+}
+
+i32 JSON_fprint(FILE *w, JSON json) {
+    switch (json.type) {
+    case JSON_STRING:
+        fprintf(w, "\"");
+        Str_fprint(w, json.as.string);
+        return fprintf(w, "\"");
+    case JSON_INTEGER:
+        return fprintf(w, "%d", json.as.integer);
+    case JSON_FLOAT:
+        return fprintf(w, "%f", json.as.floating);
+    case JSON_NULL:
+        return fprintf(w, "null");
+    case JSON_BOOL:
+        return fprintf(w, "%s", json.as.boolean ? "true" : "false");
+    case JSON_ARRAY:
+        fprintf(w, "[");
+        for (size i = 0; i < json.as.array.len; i++) {
+            JSON value = *Vec_get(json.as.array, JSON, i);
+            JSON_fprint(w, value);
+            if (i < json.as.array.len - 1) fprintf(w, ", ");
+        }
+        fprintf(w, "]");
+        return 0;
+    case JSON_OBJECT:
+        fprintf(w, "{");
+        for (size i = 0; i < json.as.object.len; i++) {
+            Str key = *Vec_get(json.as.object.keys, Str, i);
+            fprintf(w, "\"");
+            Str_fprint(w, key);
+            fprintf(w, "\": ");
+            JSON value = *Vec_get(json.as.object.values, JSON, i);
+            JSON_fprint(w, value);
+            if (i < json.as.object.len - 1) fprintf(w, ", ");
+        }
+        fprintf(w, "}");
+        return 0;
+    }
+    assert(false);
+}
+
+typedef struct {
+    JSON value;
+    uptr pos;
+} parse_result;
+
+parse_result parse_any(Arena *a, byte *src, uptr pos);
+
+parse_result parse_number(byte *src, uptr start_pos) {
+    parse_result result = {0};
+    result.pos = start_pos;
+    i32 integer = 0;
+    while (isdigit(src[result.pos])) {
+        integer = integer * 10 + (src[result.pos] - '0');
+        result.pos++;
+    }
+    if (src[result.pos] != '.') {
+        result.value = JSON_integer(integer);
+        return result;
+    }
+    result.pos++;
+    f32 fractional_part = 0.0;
+    f32 decimal_place = 0.1;
+    while (isdigit(src[result.pos])) {
+        fractional_part += (src[result.pos] - '0') * decimal_place;
+        decimal_place *= 0.1;
+        result.pos++;
+    }
+    result.value = JSON_float((f32)integer + fractional_part);
+    return result;
+}
+
+uptr absorb_whitespaces(byte *src, uptr start_pos) {
+    uptr pos = start_pos;
+    while (isspace(src[pos])) {
+        pos++;
+    }
+    return pos;
+}
+
+parse_result parse_array(Arena *a, byte *src, uptr start_pos) {
+    assert(src[start_pos] == '[');
+    parse_result result = {0};
+    result.pos = start_pos + 1;
+    if (src[result.pos] == ']') {
+        result.pos++;
+        return result;
+    }
+    Vec items = Vec_new(a, JSON, 2);
+    for (;;) {
+        result.pos = absorb_whitespaces(src, result.pos);
+        parse_result item_result = parse_any(a, src, result.pos);
+        Vec_push(a, &items, &item_result.value);
+        result.pos = absorb_whitespaces(src, item_result.pos);
+        if (src[result.pos] == ',') {
+            result.pos++;
+        } else {
+            break;
+        }
+    };
+    assert(src[result.pos] == ']');
+    result.pos++;
+    result.value = JSON_array(items);
+    return result;
+}
+
+parse_result parse_string(Arena *a, byte *src, uptr start_pos) {
+    assert(src[start_pos] == '"');
+    parse_result result = {0};
+    result.pos = start_pos + 1;
+
+    while (src[result.pos] != '"' && src[result.pos - 1] != '\\') {
+        result.pos++;
+    }
+    assert(src[result.pos] == '"');
+    result.value = JSON_string(
+        Str_copy(a, &src[start_pos + 1], result.pos - start_pos - 1));
+    result.pos++;
+
+    return result;
+}
+
+parse_result parse_object(Arena *a, byte *src, uptr start_pos) {
+    assert(src[start_pos] == '{');
+    parse_result result = {0};
+    result.pos = absorb_whitespaces(src, start_pos + 1);
+    size len = 0;
+    Vec keys = Vec_new(a, Str, 2);
+    Vec values = Vec_new(a, JSON, 2);
+    if (src[result.pos] == '}') {
+        result.pos++;
+        result.value = JSON_object(len, keys, values);
+        return result;
+    }
+    for (;;) {
+        assert(src[result.pos] == '"');
+        parse_result key_result = parse_string(a, src, result.pos);
+        result.pos = absorb_whitespaces(src, key_result.pos);
+        assert(src[result.pos] == ':');
+        result.pos = absorb_whitespaces(src, result.pos + 1);
+        parse_result value_result = parse_any(a, src, result.pos);
+        len++;
+        assert(key_result.value.type == JSON_STRING);
+        Vec_push(a, &keys, &key_result.value.as.string);
+        Vec_push(a, &values, &value_result.value);
+        result.pos = absorb_whitespaces(src, value_result.pos);
+        if (src[result.pos] != ',') {
+            break;
+        }
+        result.pos = absorb_whitespaces(src, result.pos + 1);
+    }
+    assert(src[result.pos] == '}');
+    result.pos++;
+    result.value = JSON_object(len, keys, values);
+    return result;
+}
+
+parse_result parse_any(Arena *a, byte *src, uptr pos) {
+    pos = absorb_whitespaces(src, pos);
+    if (isdigit(src[pos])) return parse_number(src, pos);
+    if (src[pos] == '[') return parse_array(a, src, pos);
+    if (src[pos] == '"') return parse_string(a, src, pos);
+    if (src[pos] == '{') return parse_object(a, src, pos);
+    if (memcmp(src + pos, "true", 4) == 0) {
+        parse_result result = {0};
+        result.value = JSON_boolean(true);
+        result.pos = pos + 4;
+        return result;
+    }
+    if (memcmp(src + pos, "false", 5) == 0) {
+        parse_result result = {0};
+        result.value = JSON_boolean(false);
+        result.pos = pos + 5;
+        return result;
+    }
+    if (memcmp(src + pos, "null", 4) == 0) {
+        parse_result result = {0};
+        result.value = JSON_null();
+        result.pos = pos + 4;
+        return result;
+    }
+    assert(false);
+}
+
+JSON JSON_parse(Arena *a, byte *src) { return parse_any(a, src, 0).value; }
+
+JSON *JSONObject_get(JSONObject obj, Str key) {
+    for (size i = 0; i < obj.len; i++) {
+        if (Str_equals(*Vec_get(obj.keys, Str, i), key)) {
+            return Vec_get(obj.values, JSON, i);
+        }
+    }
+    assert(false);
+}