LibJS: Add JSON.stringify

1 files changed, 373 insertions, 0 deletions

diff --git a/Libraries/LibJS/Runtime/JSONObject.cpp b/Libraries/LibJS/Runtime/JSONObject.cpp
new file mode 100644
index 0000000000..dae2b5af5f
--- /dev/null
+++ b/Libraries/LibJS/Runtime/JSONObject.cpp
@@ -0,0 +1,373 @@
+/*
+ * Copyright (c) 2020, Matthew Olsson <matthewcolsson@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StringBuilder.h>
+#include <LibJS/Interpreter.h>
+#include <LibJS/Runtime/Array.h>
+#include <LibJS/Runtime/Error.h>
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/JSONObject.h>
+#include <LibJS/Runtime/Object.h>
+
+namespace JS {
+
+JSONObject::JSONObject()
+    : Object(interpreter().global_object().object_prototype())
+{
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function("stringify", stringify, 3, attr);
+    define_native_function("parse", parse, 1, attr);
+}
+
+JSONObject::~JSONObject()
+{
+}
+
+Value JSONObject::stringify(Interpreter& interpreter)
+{
+    if (!interpreter.argument_count())
+        return js_undefined();
+    auto value = interpreter.argument(0);
+    auto replacer = interpreter.argument(1);
+    auto space = interpreter.argument(2);
+
+    StringifyState state;
+
+    if (replacer.is_object()) {
+        if (replacer.as_object().is_function()) {
+            state.replacer_function = &replacer.as_function();
+        } else if (replacer.is_array()) {
+            auto& replacer_object = replacer.as_object();
+            auto replacer_length = length_of_array_like(interpreter, replacer);
+            if (interpreter.exception())
+                return {};
+            Vector<String> list;
+            for (size_t i = 0; i < replacer_length; ++i) {
+                auto replacer_value = replacer_object.get(i);
+                if (interpreter.exception())
+                    return {};
+                String item;
+                if (replacer_value.is_string() || replacer_value.is_number()) {
+                    item = replacer_value.to_string(interpreter);
+                    if (interpreter.exception())
+                        return {};
+                } else if (replacer_value.is_object()) {
+                    auto& value_object = replacer_value.as_object();
+                    if (value_object.is_string_object() || value_object.is_number_object()) {
+                        item = value_object.value_of().to_string(interpreter);
+                        if (interpreter.exception())
+                            return { };
+                    }
+                }
+                if (!item.is_null() && !list.contains_slow(item)) {
+                    list.append(item);
+                }
+            }
+            state.property_list = list;
+        }
+    }
+
+    if (space.is_object()) {
+        auto& space_obj = space.as_object();
+        if (space_obj.is_string_object() || space_obj.is_number_object())
+            space = space_obj.value_of();
+    }
+
+    if (space.is_number()) {
+        StringBuilder gap_builder;
+        auto gap_size = min(10, space.as_i32());
+        for (auto i = 0; i < gap_size; ++i)
+            gap_builder.append(' ');
+        state.gap = gap_builder.to_string();
+    } else if (space.is_string()) {
+        auto string = space.as_string().string();
+        if (string.length() <= 10) {
+            state.gap = string;
+        } else {
+            state.gap = string.substring(0, 10);
+        }
+    } else {
+        state.gap = String::empty();
+    }
+
+    auto* wrapper = Object::create_empty(interpreter, interpreter.global_object());
+    wrapper->define_property(String::empty(), value);
+    if (interpreter.exception())
+        return {};
+    auto result = serialize_json_property(interpreter, state, String::empty(), wrapper);
+    if (interpreter.exception())
+        return {};
+    if (result.is_null())
+        return js_undefined();
+    return js_string(interpreter, result);
+}
+
+String JSONObject::serialize_json_property(Interpreter& interpreter, StringifyState& state, const PropertyName& key, Object* holder)
+{
+    auto value = holder->get(key);
+    if (value.is_object()) {
+        auto to_json = value.as_object().get("toJSON");
+        if (interpreter.exception())
+            return {};
+        if (to_json.is_function()) {
+            MarkedValueList arguments(interpreter.heap());
+            arguments.append(js_string(interpreter, key.to_string()));
+            value = interpreter.call(to_json.as_function(), value, move(arguments));
+            if (interpreter.exception())
+                return {};
+        }
+    }
+
+    if (state.replacer_function) {
+        MarkedValueList arguments(interpreter.heap());
+        arguments.values().append(js_string(interpreter, key.to_string()));
+        arguments.values().append(value);
+        value = interpreter.call(*state.replacer_function, holder, move(arguments));
+        if (interpreter.exception())
+            return {};
+    }
+
+    if (value.is_object()) {
+        auto& value_object = value.as_object();
+        if (value_object.is_number_object() || value_object.is_boolean_object() || value_object.is_string_object() || value_object.is_bigint_object())
+            value = value_object.value_of();
+    }
+
+    if (value.is_null())
+        return "null";
+    if (value.is_boolean())
+        return value.as_bool() ? "true" : "false";
+    if (value.is_string())
+        return quote_json_string(value.as_string().string());
+    if (value.is_number()) {
+        if (value.is_finite_number())
+            return value.to_string(interpreter);
+        return "null";
+    }
+    if (value.is_object() && !value.is_function()) {
+        if (value.is_array())
+            return serialize_json_array(interpreter, state, static_cast<Array&>(value.as_object()));
+        return serialize_json_object(interpreter, state, value.as_object());
+    }
+    if (value.is_bigint())
+        interpreter.throw_exception<TypeError>(ErrorType::JsonBigInt);
+    return {};
+}
+
+String JSONObject::serialize_json_object(Interpreter& interpreter, StringifyState& state, Object& object)
+{
+    if (state.seen_objects.contains(&object)) {
+        interpreter.throw_exception<TypeError>(ErrorType::JsonCircular);
+        return {};
+    }
+
+    state.seen_objects.set(&object);
+    String previous_indent = state.indent;
+    state.indent = String::format("%s%s", state.indent.characters(), state.gap.characters());
+    Vector<String> property_strings;
+
+    auto process_property = [&](const PropertyName& key) {
+        auto serialized_property_string = serialize_json_property(interpreter, state, key, &object);
+        if (interpreter.exception())
+            return;
+        if (!serialized_property_string.is_null()) {
+            property_strings.append(String::format(
+                "%s:%s%s",
+                quote_json_string(key.to_string()).characters(),
+                state.gap.is_empty() ? "" : " ",
+                serialized_property_string.characters()
+            ));
+        }
+    };
+
+    if (state.property_list.has_value()) {
+        auto property_list = state.property_list.value();
+        for (auto& property : property_list) {
+            process_property(property);
+            if (interpreter.exception())
+                return {};
+        }
+    } else {
+        for (auto& entry : object.indexed_properties()) {
+            auto value_and_attributes = entry.value_and_attributes(&object);
+            if (!value_and_attributes.attributes.is_enumerable())
+                continue;
+            process_property(entry.index());
+            if (interpreter.exception())
+                return {};
+        }
+        for (auto&[key, metadata] : object.shape().property_table_ordered()) {
+            if (!metadata.attributes.is_enumerable())
+                continue;
+            process_property(key);
+            if (interpreter.exception())
+                return {};
+        }
+    }
+    StringBuilder builder;
+    if (property_strings.is_empty()) {
+        builder.append("{}");
+    } else {
+        bool first = true;
+        builder.append('{');
+        if (state.gap.is_empty()) {
+            for (auto& property_string : property_strings) {
+                if (!first)
+                    builder.append(',');
+                first = false;
+                builder.append(property_string);
+            }
+        } else {
+            builder.append('\n');
+            builder.append(state.indent);
+            auto separator = String::format(",\n%s", state.indent.characters());
+            for (auto& property_string : property_strings) {
+                if (!first)
+                    builder.append(separator);
+                first = false;
+                builder.append(property_string);
+            }
+            builder.append('\n');
+            builder.append(previous_indent);
+        }
+        builder.append('}');
+    }
+
+    state.seen_objects.remove(&object);
+    state.indent = previous_indent;
+    return builder.to_string();
+}
+
+String JSONObject::serialize_json_array(Interpreter& interpreter, StringifyState& state, Object& object)
+{
+    if (state.seen_objects.contains(&object)) {
+        interpreter.throw_exception<TypeError>(ErrorType::JsonCircular);
+        return {};
+    }
+
+    state.seen_objects.set(&object);
+    String previous_indent = state.indent;
+    state.indent = String::format("%s%s", state.indent.characters(), state.gap.characters());
+    Vector<String> property_strings;
+
+    auto length = length_of_array_like(interpreter, Value(&object));
+    if (interpreter.exception())
+        return {};
+    for (size_t i = 0; i < length; ++i) {
+        if (interpreter.exception())
+            return {};
+        auto serialized_property_string = serialize_json_property(interpreter, state, i, &object);
+        if (interpreter.exception())
+            return {};
+        if (serialized_property_string.is_null()) {
+            property_strings.append("null");
+        } else {
+            property_strings.append(serialized_property_string);
+        }
+    }
+
+    StringBuilder builder;
+    if (property_strings.is_empty()) {
+        builder.append("[]");
+    } else {
+        if (state.gap.is_empty()) {
+            builder.append('[');
+            bool first = true;
+            for (auto& property_string : property_strings) {
+                if (!first)
+                    builder.append(',');
+                first = false;
+                builder.append(property_string);
+            }
+            builder.append(']');
+        } else {
+            builder.append("[\n");
+            builder.append(state.indent);
+            auto separator = String::format(",\n%s", state.indent.characters());
+            bool first = true;
+            for (auto& property_string : property_strings) {
+                if (!first)
+                    builder.append(separator);
+                first = false;
+                builder.append(property_string);
+            }
+            builder.append('\n');
+            builder.append(previous_indent);
+            builder.append(']');
+        }
+    }
+
+    state.seen_objects.remove(&object);
+    state.indent = previous_indent;
+    return builder.to_string();
+}
+
+String JSONObject::quote_json_string(String string)
+{
+    // FIXME: Handle UTF16
+    StringBuilder builder;
+    builder.append('"');
+    for (auto& ch : string) {
+        switch (ch) {
+        case '\b':
+            builder.append("\\b");
+            break;
+        case '\t':
+            builder.append("\\t");
+            break;
+        case '\n':
+            builder.append("\\n");
+            break;
+        case '\f':
+            builder.append("\\f");
+            break;
+        case '\r':
+            builder.append("\\r");
+            break;
+        case '"':
+            builder.append("\\\"");
+            break;
+        case '\\':
+            builder.append("\\\\");
+            break;
+        default:
+            if (ch < 0x20) {
+                builder.append("\\u%#08x", ch);
+            } else {
+                builder.append(ch);
+            }
+        }
+    }
+    builder.append('"');
+    return builder.to_string();
+}
+
+Value JSONObject::parse(Interpreter&)
+{
+    return js_undefined();
+}
+
+}