Add declare to parser

src/extra/ast.ts

@@ -1677,6 +1677,9 @@ export class ASTBuilder {
 
   serializeAccessModifiers(node: DeclarationStatement): void {
     var sb = this.sb;
+    if (node.is(CommonFlags.DECLARE)) {
+      sb.push("declare ");
+    }
     if (node.is(CommonFlags.PUBLIC)) {
       sb.push("public ");
     } else if (node.is(CommonFlags.PRIVATE)) {

src/parser.ts

@@ -1839,6 +1839,7 @@ export class Parser extends DiagnosticEmitter {
   ): Node | null {
 
     // before:
+    //   'declare'?
     //   ('public' | 'private' | 'protected')?
     //   ('static' | 'abstract')?
     //   'readonly'?
@@ -1870,6 +1871,44 @@ export class Parser extends DiagnosticEmitter {
     // implemented methods are virtual
     if (isInterface) flags |= CommonFlags.VIRTUAL;
 
+    var declareStart = 0;
+    var declareEnd = 0;
+    var contextIsAmbient = parent.is(CommonFlags.AMBIENT);
+    if (tn.peek() == Token.DECLARE) {
+      let state = tn.mark();
+      tn.next();
+      if (tn.peek() != Token.COLON) { // modifier
+        tn.discard(state);
+        if (isInterface) {
+          this.error(
+            DiagnosticCode._0_modifier_cannot_be_used_here,
+            tn.range(), "declare"
+          );
+        } else {
+          if (contextIsAmbient) {
+            this.error(
+              DiagnosticCode.A_declare_modifier_cannot_be_used_in_an_already_ambient_context,
+              tn.range()
+            ); // recoverable
+          } else {
+            this.error(
+              DiagnosticCode.Not_implemented_0,
+              tn.range(), "Ambient fields"
+            ); // recoverable
+
+            flags |= CommonFlags.DECLARE | CommonFlags.AMBIENT;
+            declareStart = tn.tokenPos;
+            declareEnd = tn.pos;
+          }
+        }
+        if (!startPos) startPos = tn.tokenPos;
+      } else { // identifier
+        tn.reset(state);
+      }
+    } else if (contextIsAmbient) {
+      flags |= CommonFlags.AMBIENT;
+    }
+
     var accessStart = 0;
     var accessEnd = 0;
     if (tn.skip(Token.PUBLIC)) {
@@ -2108,6 +2147,13 @@ export class Parser extends DiagnosticEmitter {
 
     // method: '(' Parameters (':' Type)? '{' Statement* '}' ';'?
     if (tn.skip(Token.OPENPAREN)) {
+      if (flags & CommonFlags.DECLARE) {
+        this.error(
+          DiagnosticCode._0_modifier_cannot_be_used_here,
+          tn.range(declareStart, declareEnd), "declare"
+        ); // recoverable
+      }
+
       let signatureStart = tn.tokenPos;
       let parameters = this.parseParameters(tn, isConstructor);
       if (!parameters) return null;
@@ -2291,6 +2337,12 @@ export class Parser extends DiagnosticEmitter {
       }
       let initializer: Expression | null = null;
       if (tn.skip(Token.EQUALS)) {
+        if (flags & CommonFlags.AMBIENT) {
+          this.error(
+            DiagnosticCode.Initializers_are_not_allowed_in_ambient_contexts,
+            tn.range()
+          ); // recoverable
+        }
         initializer = this.parseExpression(tn);
         if (!initializer) return null;
       }

tests/parser/class.ts

@@ -26,4 +26,16 @@ export class Invalid<T> {
   // 1049: A 'set' accessor must have exactly one parameter.
   // 1095: A 'set' accessor cannot have a return type annotation.
   set instanceSetter<T>(): i32 {}
+
+  // 100: Not implemented: Ambient fields
+  declare declareField: i32;
+
+  // 100: Not implemented: Ambient fields
+  // 1039: Initializers are not allowed in ambient contexts.
+  declare declareInitializer: i32 = 0;
+
+  // 100: Not implemented: Ambient fields
+  // 1042: 'declare' modifier cannot be used here.
+  // 1183: An implementation cannot be declared in ambient contexts.
+  declare declareMethod(): i32 {}
 }

tests/parser/class.ts.fixture.ts

@@ -14,6 +14,9 @@ export class Invalid<T> {
   instanceFunction() {}
   get instanceGetter<T>(a: i32) {}
   set instanceSetter<T>() {}
+  declare declareField: i32;
+  declare declareInitializer: i32 = 0;
+  declare declareMethod(): i32 {}
 }
 // ERROR 1092: "Type parameters cannot appear on a constructor declaration." in class.ts(15,14+3)
 // ERROR 1110: "Type expected." in class.ts(18,21+0)
@@ -23,3 +26,9 @@ export class Invalid<T> {
 // ERROR 1094: "An accessor cannot have type parameters." in class.ts(28,21+3)
 // ERROR 1049: "A 'set' accessor must have exactly one parameter." in class.ts(28,7+14)
 // ERROR 1095: "A 'set' accessor cannot have a return type annotation." in class.ts(28,26+1)
+// ERROR 100: "Not implemented: Ambient fields" in class.ts(31,3+7)
+// ERROR 100: "Not implemented: Ambient fields" in class.ts(35,3+7)
+// ERROR 1039: "Initializers are not allowed in ambient contexts." in class.ts(35,35+1)
+// ERROR 100: "Not implemented: Ambient fields" in class.ts(40,3+7)
+// ERROR 1042: "'declare' modifier cannot be used here." in class.ts(40,3+7)
+// ERROR 1183: "An implementation cannot be declared in ambient contexts." in class.ts(40,32+1)