sebastienros.jint/Jint/EsprimaExtensions.cs

using System.Runtime.CompilerServices;
using Esprima;
using Esprima.Ast;
using Jint.Native;
using Jint.Native.Function;
using Jint.Native.Object;
using Jint.Runtime;
using Jint.Runtime.Environments;
using Jint.Runtime.Interpreter;
using Jint.Runtime.Interpreter.Expressions;
using Jint.Runtime.Modules;

namespace Jint
{
    public static class EsprimaExtensions
    {
        public static JsValue GetKey<T>(this T property, Engine engine) where T : IProperty => GetKey(property.Key, engine, property.Computed);

        public static JsValue GetKey(this Expression expression, Engine engine, bool resolveComputed = false)
        {
            var key = TryGetKey(expression, engine, resolveComputed);
            if (key is not null)
            {
                return TypeConverter.ToPropertyKey(key);
            }

            ExceptionHelper.ThrowArgumentException("Unable to extract correct key, node type: " + expression.Type);
            return JsValue.Undefined;
        }

        internal static JsValue TryGetKey<T>(this T property, Engine engine) where T : IProperty
        {
            return TryGetKey(property.Key, engine, property.Computed);
        }

        internal static JsValue TryGetKey<T>(this T expression, Engine engine, bool resolveComputed) where T : Expression
        {
            JsValue key;
            if (expression is Literal literal)
            {
                key = literal.TokenType == TokenType.NullLiteral ? JsValue.Null : LiteralKeyToString(literal);
            }
            else if (!resolveComputed && expression is Identifier identifier)
            {
                key = identifier.Name;
            }
            else if (resolveComputed)
            {
                return TryGetComputedPropertyKey(expression, engine);
            }
            else
            {
                key = JsValue.Undefined;
            }
            return key;
        }

        private static JsValue TryGetComputedPropertyKey<T>(T expression, Engine engine)
            where T : Expression
        {
            if (expression.Type is Nodes.Identifier
                or Nodes.CallExpression
                or Nodes.BinaryExpression
                or Nodes.UpdateExpression
                or Nodes.AssignmentExpression
                or Nodes.UnaryExpression
                or Nodes.MemberExpression
                or Nodes.LogicalExpression
                or Nodes.ConditionalExpression
                or Nodes.ArrowFunctionExpression
                or Nodes.FunctionExpression
                or Nodes.YieldExpression
                or Nodes.TemplateLiteral)
            {
                var context = engine._activeEvaluationContext;
                return JintExpression.Build(expression).GetValue(context!);
            }

            return JsValue.Undefined;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal static bool IsFunctionDefinition<T>(this T node) where T : Node
        {
            var type = node.Type;
            return type
                is Nodes.FunctionExpression
                or Nodes.ArrowFunctionExpression
                or Nodes.ArrowParameterPlaceHolder
                or Nodes.ClassExpression;
        }

        /// <summary>
        /// https://tc39.es/ecma262/#sec-static-semantics-isconstantdeclaration
        /// </summary>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal static bool IsConstantDeclaration(this Declaration d)
        {
            return d is VariableDeclaration { Kind: VariableDeclarationKind.Const };
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal static bool HasName<T>(this T node) where T : Node
        {
            if (!node.IsFunctionDefinition())
            {
                return false;
            }

            if ((node as IFunction)?.Id is not null)
            {
                return true;
            }

            if ((node as ClassExpression)?.Id is not null)
            {
                return true;
            }

            return false;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal static bool IsAnonymousFunctionDefinition<T>(this T node) where T : Node
        {
            if (!node.IsFunctionDefinition())
            {
                return false;
            }

            if (node.HasName())
            {
                return false;
            }

            return true;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal static bool IsOptional<T>(this T node) where T : Expression
        {
            switch (node)
            {
                case MemberExpression { Optional: true }:
                case CallExpression { Optional: true }:
                    return true;
                default:
                    return false;
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal static string LiteralKeyToString(Literal literal)
        {
            // prevent conversion to scientific notation
            if (literal.Value is double d)
            {
                return TypeConverter.ToString(d);
            }

            return literal.Value as string ?? Convert.ToString(literal.Value, provider: null) ?? "";
        }

        internal static void GetBoundNames(this VariableDeclaration variableDeclaration, List<string> target)
        {
            ref readonly var declarations = ref variableDeclaration.Declarations;
            for (var i = 0; i < declarations.Count; i++)
            {
                var declaration = declarations[i];
                GetBoundNames(declaration.Id, target);
            }
        }

        internal static void GetBoundNames(this Node? parameter, List<string> target)
        {
            if (parameter is null || parameter.Type == Nodes.Literal)
            {
                return;
            }

            // try to get away without a loop
            if (parameter is Identifier id)
            {
                target.Add(id.Name);
                return;
            }

            if (parameter is VariableDeclaration variableDeclaration)
            {
                variableDeclaration.GetBoundNames(target);
                return;
            }

            while (true)
            {
                if (parameter is Identifier identifier)
                {
                    target.Add(identifier.Name);
                    return;
                }

                if (parameter is RestElement restElement)
                {
                    parameter = restElement.Argument;
                    continue;
                }

                if (parameter is ArrayPattern arrayPattern)
                {
                    ref readonly var arrayPatternElements = ref arrayPattern.Elements;
                    for (var i = 0; i < arrayPatternElements.Count; i++)
                    {
                        var expression = arrayPatternElements[i];
                        GetBoundNames(expression, target);
                    }
                }
                else if (parameter is ObjectPattern objectPattern)
                {
                    ref readonly var objectPatternProperties = ref objectPattern.Properties;
                    for (var i = 0; i < objectPatternProperties.Count; i++)
                    {
                        var property = objectPatternProperties[i];
                        if (property is Property p)
                        {
                            GetBoundNames(p.Value, target);
                        }
                        else
                        {
                            GetBoundNames((RestElement) property, target);
                        }
                    }
                }
                else if (parameter is AssignmentPattern assignmentPattern)
                {
                    parameter = assignmentPattern.Left;
                    continue;
                }
                else if (parameter is ClassDeclaration classDeclaration)
                {
                    var name = classDeclaration.Id?.Name;
                    if (name != null)
                    {
                        target.Add(name);
                    }
                }

                break;
            }
        }

        internal static void BindingInitialization(
            this Node? expression,
            EvaluationContext context,
            JsValue value,
            EnvironmentRecord env)
        {
            if (expression is Identifier identifier)
            {
                var catchEnvRecord = (DeclarativeEnvironmentRecord) env;
                catchEnvRecord.CreateMutableBindingAndInitialize(identifier.Name, canBeDeleted: false, value);
            }
            else if (expression is BindingPattern bindingPattern)
            {
                BindingPatternAssignmentExpression.ProcessPatterns(
                    context,
                    bindingPattern,
                    value,
                    env);
            }
        }

        /// <summary>
        /// https://tc39.es/ecma262/#sec-runtime-semantics-definemethod
        /// </summary>
        internal static Record DefineMethod<T>(this T m, ObjectInstance obj, ObjectInstance? functionPrototype = null) where T : IProperty
        {
            var engine = obj.Engine;
            var propKey = TypeConverter.ToPropertyKey(m.GetKey(engine));
            var intrinsics = engine.Realm.Intrinsics;

            var runningExecutionContext = engine.ExecutionContext;
            var scope = runningExecutionContext.LexicalEnvironment;
            var privateScope= runningExecutionContext.PrivateEnvironment;

            var prototype = functionPrototype ?? intrinsics.Function.PrototypeObject;
            var function = m.Value as IFunction;
            if (function is null)
            {
                ExceptionHelper.ThrowSyntaxError(engine.Realm);
            }

            var definition = new JintFunctionDefinition(function);
            var closure = intrinsics.Function.OrdinaryFunctionCreate(prototype, definition, definition.ThisMode, scope, privateScope);
            closure.MakeMethod(obj);

            return new Record(propKey, closure);
        }

        internal static void GetImportEntries(this ImportDeclaration import, List<ImportEntry> importEntries, HashSet<string> requestedModules)
        {
            var source = import.Source.StringValue!;
            var specifiers = import.Specifiers;
            requestedModules.Add(source);

            foreach (var specifier in specifiers)
            {
                switch (specifier)
                {
                    case ImportNamespaceSpecifier namespaceSpecifier:
                        importEntries.Add(new ImportEntry(source, "*", namespaceSpecifier.Local.GetModuleKey()));
                        break;
                    case ImportSpecifier importSpecifier:
                        importEntries.Add(new ImportEntry(source, importSpecifier.Imported.GetModuleKey(), importSpecifier.Local.GetModuleKey()));
                        break;
                    case ImportDefaultSpecifier defaultSpecifier:
                        importEntries.Add(new ImportEntry(source, "default", defaultSpecifier.Local.GetModuleKey()));
                        break;
                }
            }
        }

        internal static void GetExportEntries(this ExportDeclaration export, List<ExportEntry> exportEntries, HashSet<string> requestedModules)
        {
            switch (export)
            {
                case ExportDefaultDeclaration defaultDeclaration:
                    GetExportEntries(true, defaultDeclaration.Declaration, exportEntries);
                    break;
                case ExportAllDeclaration allDeclaration:
                    //Note: there is a pending PR for Esprima to support exporting an imported modules content as a namespace i.e. 'export * as ns from "mod"'
                    requestedModules.Add(allDeclaration.Source.StringValue!);
                    exportEntries.Add(new(allDeclaration.Exported?.GetModuleKey(), allDeclaration.Source.StringValue, "*", null));
                    break;
                case ExportNamedDeclaration namedDeclaration:
                    ref readonly var specifiers = ref namedDeclaration.Specifiers;
                    if (specifiers.Count == 0)
                    {
                        GetExportEntries(false, namedDeclaration.Declaration!, exportEntries, namedDeclaration.Source?.StringValue);
                    }
                    else
                    {
                        for (var i = 0; i < specifiers.Count; i++)
                        {
                            var specifier = specifiers[i];
                            if (namedDeclaration.Source != null)
                            {
                                exportEntries.Add(new(specifier.Exported.GetModuleKey(), namedDeclaration.Source.StringValue, specifier.Local.GetModuleKey(), null));
                            }
                            else
                            {
                                exportEntries.Add(new(specifier.Exported.GetModuleKey(), null, null, specifier.Local.GetModuleKey()));
                            }
                        }
                    }

                    if (namedDeclaration.Source is not null)
                    {
                        requestedModules.Add(namedDeclaration.Source.StringValue!);
                    }

                    break;
            }
        }

        private static void GetExportEntries(bool defaultExport, StatementListItem declaration, List<ExportEntry> exportEntries, string? moduleRequest = null)
        {
            var names = GetExportNames(declaration);

            if (names.Count == 0)
            {
                if (defaultExport)
                {
                    exportEntries.Add(new("default", null, null, "*default*"));
                }
            }
            else
            {
                for (var i = 0; i < names.Count; i++)
                {
                    var name = names[i];
                    var exportName = defaultExport ? "default" : name;
                    exportEntries.Add(new(exportName, moduleRequest, null, name));
                }
            }
        }

        private static List<string> GetExportNames(StatementListItem declaration)
        {
            var result = new List<string>();

            switch (declaration)
            {
                case FunctionDeclaration functionDeclaration:
                    var funcName = functionDeclaration.Id?.Name;
                    if (funcName is not null)
                    {
                        result.Add(funcName);
                    }

                    break;
                case ClassDeclaration classDeclaration:
                    var className = classDeclaration.Id?.Name;
                    if (className is not null)
                    {
                        result.Add(className);
                    }

                    break;
                case VariableDeclaration variableDeclaration:
                    ref readonly var declarators = ref variableDeclaration.Declarations;
                    for (var i = 0; i < declarators.Count; i++)
                    {
                        var declarator = declarators[i];
                        var varName = declarator.Id.As<Identifier>()?.Name;
                        if (varName is not null)
                        {
                            result.Add(varName);
                        }
                    }

                    break;
            }

            return result;
        }

        private static string? GetModuleKey(this Expression expression)
        {
            return (expression as Identifier)?.Name ?? (expression as Literal)?.StringValue;
        }

        internal readonly record struct Record(JsValue Key, ScriptFunctionInstance Closure);

        /// <summary>
        /// Creates a dummy node that can be used when only location available and node is required.
        /// </summary>
        internal static SyntaxElement CreateLocationNode(in Location location)
        {
            return new MinimalSyntaxElement(location);
        }
    }

    internal sealed class MinimalSyntaxElement : SyntaxElement
    {
        public MinimalSyntaxElement(in Location location)
        {
            Location = location;
        }
    }
}