Use a separate field on a node to specify parser context flags.

src/compiler/diagnosticInformationMap.generated.ts

@@ -125,6 +125,7 @@ module ts {
         Unterminated_template_literal: { code: 1160, category: DiagnosticCategory.Error, key: "Unterminated template literal." },
         Unterminated_regular_expression_literal: { code: 1161, category: DiagnosticCategory.Error, key: "Unterminated regular expression literal." },
         An_object_member_cannot_be_declared_optional: { code: 1162, category: DiagnosticCategory.Error, key: "An object member cannot be declared optional." },
+        yield_expression_must_be_contained_within_a_generator_declaration: { code: 1163, category: DiagnosticCategory.Error, key: "'yield' expression must be contained_within a generator declaration." },
         Duplicate_identifier_0: { code: 2300, category: DiagnosticCategory.Error, key: "Duplicate identifier '{0}'." },
         Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor: { code: 2301, category: DiagnosticCategory.Error, key: "Initializer of instance member variable '{0}' cannot reference identifier '{1}' declared in the constructor." },
         Static_members_cannot_reference_class_type_parameters: { code: 2302, category: DiagnosticCategory.Error, key: "Static members cannot reference class type parameters." },

src/compiler/diagnosticMessages.json

@@ -491,6 +491,10 @@
         "category": "Error",
         "code": 1162
     },
+    "'yield' expression must be contained_within a generator declaration.": {
+        "category": "Error",
+        "code": 1163
+    },
 
     "Duplicate identifier '{0}'.": {
         "category": "Error",

src/compiler/types.ts

@@ -183,6 +183,7 @@ module ts {
         ConditionalExpression,
         TemplateExpression,
         TemplateSpan,
+        YieldExpression,
         OmittedExpression,
         // Element
         Block,
@@ -269,22 +270,30 @@ module ts {
         DeclarationFile     = 0x00000400,  // Node is a .d.ts file
         Let                 = 0x00000800,  // Variable declaration
         Const               = 0x00001000,  // Variable declaration
-
-        // Set if this node was parsed in strict mode.  Used for grammar error checks, as well as
-        // checking if the node can be reused in incremental settings.
-        ParsedInStrictModeContext = 0x00002000,
-        ParsedInDisallowInContext = 0x00004000, 
-
-        OctalLiteral        = 0x00008000,
+        OctalLiteral        = 0x00002000,
+        Generator           = 0x00004000,
+        YieldStar           = 0x00008000,
 
         Modifier = Export | Ambient | Public | Private | Protected | Static,
         AccessibilityModifier = Public | Private | Protected,
         BlockScoped = Let | Const
     }
 
+    export const enum ParserContextFlags {
+        // Set if this node was parsed in strict mode.  Used for grammar error checks, as well as
+        // checking if the node can be reused in incremental settings.
+        StrictMode          = 1 << 0,
+        DisallowIn          = 1 << 1,
+        Yield               = 1 << 2,
+        GeneratorParameter  = 1 << 3,
+    }
+
     export interface Node extends TextRange {
         kind: SyntaxKind;
         flags: NodeFlags;
+        // Specific context the parser was in when this node was created.  Normally undefined. 
+        // Only set when the parser was in some interesting context (like async/yield).
+        parserContextFlags?: ParserContextFlags;
         id?: number;                  // Unique id (used to look up NodeLinks)
         parent?: Node;                // Parent node (initialized by binding)
         symbol?: Symbol;              // Symbol declared by node (initialized by binding)
@@ -431,6 +440,10 @@ module ts {
         operator: SyntaxKind;
         operand: Expression;
     }
+
+    export interface YieldExpression extends Expression {
+        expression: Expression;
+    }
 
     export interface BinaryExpression extends Expression {
         left: Expression;

src/services/syntax/constants.ts

@@ -1,29 +1,24 @@
 ///<reference path='references.ts' />
 
 module TypeScript {
+    export const enum ParserContextFlags {
+        StrictMode          = 1 << 0,
+        DisallowIn          = 1 << 1,
+        Yield               = 1 << 2,
+        GeneratorParameter  = 1 << 3,
+
+        Mask                = 0xF
+    }
+
     export enum SyntaxNodeConstants {
         None = 0,
 
-        // Masks that we use to place information about a node into a single int.  The first bit tells
-        // us if we've computed the data for a node.
-        //
-        // The second bit tells us if the node is incrementally reusable if it does not
-        // containe any skipped tokens, zero width tokens, regex tokens in it ("/", "/=" or "/.../"), 
-        // and contains no tokens that were parser generated.
-        //
-        // The next bit lets us know if the nodes was parsed in a strict context or node.  A node can
-        // only be used by the incremental parser if it is parsed in the same strict context as before.
-        // last masks off the part of the int
-        //
+        // The first four bit of the flags are used to store parser context flags.
         // The width of the node is stored in the remainder of the int.  This allows us up to 128MB
         // for a node by using all 27 bits.  However, in the common case, we'll use less than 27 bits
         // for the width.  Thus, the info will be stored in a single int in chakra.
-        DataComputed                        = 0x00000001, // 0000 0000 0000 0000 0000 0000 0000 0001
-        IncrementallyUnusableMask           = 0x00000002, // 0000 0000 0000 0000 0000 0000 0000 0010
-        ParsedInStrictModeContext           = 0x00000004, // 0000 0000 0000 0000 0000 0000 0000 0100
-        ParsedInDisallowInContext           = 0x00000008, // 0000 0000 0000 0000 0000 0000 0000 1000
-        ParsedInYieldContext                = 0x00000010, // 0000 0000 0000 0000 0000 0000 0001 0000
-        ParsedInGeneratorParameterContext   = 0x00000020, // 0000 0000 0000 0000 0000 0000 0010 0000
-        FullWidthShift                      = 1 << 6,     // 1111 1111 1111 1111 1111 1111 1100 0000
+        DataComputed                        = 1 << 4, // 0000 0000 0000 0000 0000 0000 0001 0000
+        IncrementallyUnusableMask           = 1 << 5, // 0000 0000 0000 0000 0000 0000 0010 0000
+        FullWidthShift                      = 1 << 6, // 1111 1111 1111 1111 1111 1111 1100 0000
     }
 }