Function resolveMappedTypeMembers

test/fixtures/snapshot/typescript.js:58537–58606

Resolve the members of a mapped type { [P in K]: T }

(type)

        }
        /** Resolve the members of a mapped type { [P in K]: T } */
        function resolveMappedTypeMembers(type) {
            var members = ts.createSymbolTable();
            var indexInfos;
            // Resolve upfront such that recursive references see an empty object type.
            setStructuredTypeMembers(type, emptySymbols, ts.emptyArray, ts.emptyArray, ts.emptyArray);
            // In { [P in K]: T }, we refer to P as the type parameter type, K as the constraint type,
            // and T as the template type.
            var typeParameter = getTypeParameterFromMappedType(type);
            var constraintType = getConstraintTypeFromMappedType(type);
            var nameType = getNameTypeFromMappedType(type.target || type);
            var templateType = getTemplateTypeFromMappedType(type.target || type);
            var modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T'
            var templateModifiers = getMappedTypeModifiers(type);
            var include = keyofStringsOnly ? 128 /* TypeFlags.StringLiteral */ : 8576 /* TypeFlags.StringOrNumberLiteralOrUnique */;
            if (isMappedTypeWithKeyofConstraintDeclaration(type)) {
                // We have a { [P in keyof T]: X }
                forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, include, keyofStringsOnly, addMemberForKeyType);
            }
            else {
                forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType);
            }
            setStructuredTypeMembers(type, members, ts.emptyArray, ts.emptyArray, indexInfos || ts.emptyArray);
            function addMemberForKeyType(keyType) {
                var propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType;
                forEachType(propNameType, function (t) { return addMemberForKeyTypeWorker(keyType, t); });
            }
            function addMemberForKeyTypeWorker(keyType, propNameType) {
                // If the current iteration type constituent is a string literal type, create a property.
                // Otherwise, for type string create a string index signature.
                if (isTypeUsableAsPropertyName(propNameType)) {
                    var propName = getPropertyNameFromType(propNameType);
                    // String enum members from separate enums with identical values
                    // are distinct types with the same property name. Make the resulting
                    // property symbol's name type be the union of those enum member types.
                    var existingProp = members.get(propName);
                    if (existingProp) {
                        existingProp.nameType = getUnionType([existingProp.nameType, propNameType]);
                        existingProp.keyType = getUnionType([existingProp.keyType, keyType]);
                    }
                    else {
                        var modifiersProp = isTypeUsableAsPropertyName(keyType) ? getPropertyOfType(modifiersType, getPropertyNameFromType(keyType)) : undefined;
                        var isOptional = !!(templateModifiers & 4 /* MappedTypeModifiers.IncludeOptional */ ||
                            !(templateModifiers & 8 /* MappedTypeModifiers.ExcludeOptional */) && modifiersProp && modifiersProp.flags & 16777216 /* SymbolFlags.Optional */);
                        var isReadonly = !!(templateModifiers & 1 /* MappedTypeModifiers.IncludeReadonly */ ||
                            !(templateModifiers & 2 /* MappedTypeModifiers.ExcludeReadonly */) && modifiersProp && isReadonlySymbol(modifiersProp));
                        var stripOptional = strictNullChecks && !isOptional && modifiersProp && modifiersProp.flags & 16777216 /* SymbolFlags.Optional */;
                        var lateFlag = modifiersProp ? getIsLateCheckFlag(modifiersProp) : 0;
                        var prop = createSymbol(4 /* SymbolFlags.Property */ | (isOptional ? 16777216 /* SymbolFlags.Optional */ : 0), propName, lateFlag | 262144 /* CheckFlags.Mapped */ | (isReadonly ? 8 /* CheckFlags.Readonly */ : 0) | (stripOptional ? 524288 /* CheckFlags.StripOptional */ : 0));
                        prop.mappedType = type;
                        prop.nameType = propNameType;
                        prop.keyType = keyType;
                        if (modifiersProp) {
                            prop.syntheticOrigin = modifiersProp;
                            // If the mapped type has an `as XXX` clause, the property name likely won't match the declaration name and
                            // multiple properties may map to the same name. Thus, we attach no declarations to the symbol.
                            prop.declarations = nameType ? undefined : modifiersProp.declarations;
                        }
                        members.set(propName, prop);