Initial function expression parsing

src/ast.ts

@@ -34,6 +34,8 @@ export enum NodeKind {
   COMMA,
   ELEMENTACCESS,
   FALSE,
+  FUNCTION,
+  FUNCTIONARROW,
   LITERAL,
   NEW,
   NULL,
@@ -225,6 +227,18 @@ export abstract class Node {
     return expr;
   }
 
+  static createFunctionExpression(
+    declaration: FunctionDeclaration,
+    isArrow: bool = false
+  ): FunctionExpression {
+    var expr = isArrow
+      ? new FunctionArrowExpression()
+      : new FunctionExpression();
+    expr.range = declaration.range;
+    expr.declaration = declaration;
+    return expr;
+  }
+
   static createIntegerLiteralExpression(
     value: I64,
     range: Range
@@ -710,7 +724,7 @@ export abstract class Node {
     typeParameters: TypeParameter[],
     parameters: Parameter[],
     returnType: TypeNode | null,
-    statements: Statement[] | null,
+    body: Statement | null,
     modifiers: Modifier[] | null,
     decorators: Decorator[] | null,
     range: Range
@@ -721,7 +735,7 @@ export abstract class Node {
     stmt.typeParameters = typeParameters; setParent(typeParameters, stmt);
     stmt.parameters = parameters; setParent(parameters, stmt);
     stmt.returnType = returnType; if (returnType) returnType.parent = stmt;
-    stmt.statements = statements; if (statements) setParent(statements, stmt);
+    stmt.body = body; if (body) body.parent = stmt;
     stmt.modifiers = modifiers; if (modifiers) setParent(modifiers, stmt);
     stmt.decorators = decorators; if (decorators) setParent(decorators, stmt);
     return stmt;
@@ -732,7 +746,7 @@ export abstract class Node {
     typeParameters: TypeParameter[],
     parameters: Parameter[],
     returnType: TypeNode | null,
-    statements: Statement[] | null,
+    body: Statement | null,
     modifiers: Modifier[] | null,
     decorators: Decorator[] | null,
     range: Range
@@ -743,7 +757,7 @@ export abstract class Node {
     stmt.typeParameters = typeParameters; setParent(typeParameters, stmt);
     stmt.parameters = parameters; setParent(parameters, stmt);
     stmt.returnType = returnType; if (returnType) returnType.parent = stmt;
-    stmt.statements = statements; if (statements) setParent(statements, stmt);
+    stmt.body = body; if (body) body.parent = stmt;
     stmt.modifiers = modifiers; if (modifiers) setParent(modifiers, stmt);
     stmt.decorators = decorators; if (decorators) setParent(decorators, stmt);
     return stmt;
@@ -1033,6 +1047,19 @@ export class FloatLiteralExpression extends LiteralExpression {
   value: f64;
 }
 
+/** Represents a function expression using the 'function' keyword. */
+export class FunctionExpression extends Expression {
+  kind = NodeKind.FUNCTION;
+
+  /** Inline function declaration. */
+  declaration: FunctionDeclaration;
+}
+
+/** Represents an arrow function expression. */
+export class FunctionArrowExpression extends FunctionExpression {
+  kind = NodeKind.FUNCTIONARROW;
+}
+
 /** Represents an integer literal expression. */
 export class IntegerLiteralExpression extends LiteralExpression {
   literalKind = LiteralKind.INTEGER;
@@ -1468,8 +1495,8 @@ export class FunctionDeclaration extends DeclarationStatement {
   parameters: Parameter[];
   /** Return type. */
   returnType: TypeNode | null;
-  /** Contained statements. */
+  /** Body statement. Usually a block. */
-  statements: Statement[] | null;
+  body: Statement | null;
 }
 
 /** Represents an `if` statement. */

src/compiler.ts

@@ -729,14 +729,14 @@ export class Compiler extends DiagnosticEmitter {
 
     var declaration = instance.prototype.declaration;
     if (instance.is(ElementFlags.DECLARED)) {
-      if (declaration.statements) {
+      if (declaration.body) {
         this.error(
           DiagnosticCode.An_implementation_cannot_be_declared_in_ambient_contexts,
           declaration.name.range
         );
         return false;
       }
-    } else if (!declaration.statements) {
+    } else if (!declaration.body) {
       this.error(
         DiagnosticCode.Function_implementation_is_missing_or_not_immediately_following_the_declaration,
         declaration.name.range
@@ -748,12 +748,12 @@ export class Compiler extends DiagnosticEmitter {
     instance.set(ElementFlags.COMPILED);
 
     // compile statements
-    var stmts: ExpressionRef[] | null = null;
+    var stmt: ExpressionRef = 0;
     if (!instance.is(ElementFlags.DECLARED)) {
       var previousFunction = this.currentFunction;
       this.currentFunction = instance;
-      var statements = assert(declaration.statements, "implementation expected");
+      var body = assert(declaration.body, "implementation expected");
-      stmts = this.compileStatements(statements);
+      stmt = this.compileStatement(body);
       // make sure the top-level branch or all child branches return
       var allBranchesReturn = this.currentFunction.flow.finalize();
       if (instance.returnType != Type.void && !allBranchesReturn) {
@@ -810,7 +810,7 @@ export class Compiler extends DiagnosticEmitter {
         instance.internalName,
         typeRef,
         typesToNativeTypes(instance.additionalLocals),
-        this.module.createBlock(null, <ExpressionRef[]>stmts, NativeType.None)
+        assert(stmt)
       );
     }
 

src/extra/ast.ts

@@ -25,6 +25,7 @@ import {
   CallExpression,
   CommaExpression,
   ElementAccessExpression,
+  FunctionExpression,
   NewExpression,
   ParenthesizedExpression,
   PropertyAccessExpression,
@@ -124,6 +125,11 @@ export function serializeNode(node: Node, sb: string[]): void {
       serializeElementAccessExpression(<ElementAccessExpression>node, sb);
       break;
 
+    case NodeKind.FUNCTION:
+    case NodeKind.FUNCTIONARROW:
+      serializeFunctionExpression(<FunctionExpression>node, sb);
+      break;
+
     case NodeKind.LITERAL:
       serializeLiteralExpression(<LiteralExpression>node, sb);
       break;
@@ -412,6 +418,21 @@ export function serializeElementAccessExpression(node: ElementAccessExpression,
   sb.push("]");
 }
 
+export function serializeFunctionExpression(node: FunctionExpression, sb: string[]): void {
+  var declaration = node.declaration;
+  var isArrow = node.kind == NodeKind.FUNCTIONARROW;
+  if (!isArrow) {
+    if (declaration.name.text.length) {
+      sb.push("function ");
+    } else {
+      sb.push("function");
+    }
+  } else {
+    assert(declaration.name.text.length == 0);
+  }
+  serializeFunctionCommon(declaration, sb, isArrow);
+}
+
 export function serializeLiteralExpression(node: LiteralExpression, sb: string[]): void {
   switch (node.literalKind) {
 
@@ -608,15 +629,19 @@ export function serializeStatement(node: Statement, sb: string[]): void {
 
 function serializeTerminatedStatement(statement: Statement, sb: string[]): void {
   serializeStatement(statement, sb);
-  if (sb.length) { // i.e. leading EmptyStatement
+  if (
+    !sb.length ||                          // leading EmptyStatement
+    statement.kind == NodeKind.VARIABLE || // potentially assigns a FunctionExpression
+    statement.kind == NodeKind.EXPRESSION  // potentially assigns a FunctionExpression
+  ) {
+    sb.push(";\n");
+  } else {
     var last = sb[sb.length - 1];
     if (last.length && last.charCodeAt(last.length - 1) == CharCode.CLOSEBRACE) {
       sb.push("\n");
     } else {
       sb.push(";\n");
     }
-  } else {
-    sb.push(";\n");
   }
 }
 
@@ -840,11 +865,15 @@ export function serializeFunctionDeclaration(node: FunctionDeclaration, sb: stri
       sb.push(" ");
     }
   }
+  if (node.name.text.length) {
     sb.push("function ");
+  } else {
+    sb.push("function");
+  }
   serializeFunctionCommon(node, sb);
 }
 
-function serializeFunctionCommon(node: FunctionDeclaration, sb: string[]): void {
+function serializeFunctionCommon(node: FunctionDeclaration, sb: string[], isArrow: bool = false): void {
   var i: i32, k: i32;
   serializeIdentifierExpression(node.name, sb);
   if (k = node.typeParameters.length) {
@@ -864,18 +893,33 @@ function serializeFunctionCommon(node: FunctionDeclaration, sb: string[]): void
       serializeParameter(node.parameters[i], sb);
     }
   }
+  if (isArrow) {
+    if (node.body) {
+      if (node.returnType) {
+        sb.push("): ");
+        serializeTypeNode(node.returnType, sb);
+      }
+      sb.push(" => ");
+      serializeStatement(<Statement>node.body, sb);
+    } else {
+      if (node.returnType) {
+        sb.push(" => ");
+        serializeTypeNode(node.returnType, sb);
+      } else {
+        sb.push(" => void");
+      }
+    }
+  } else {
     if (node.returnType && !hasModifier(ModifierKind.SET, node.modifiers)) {
       sb.push("): ");
       serializeTypeNode(node.returnType, sb);
     } else {
       sb.push(")");
     }
-  if (node.statements) {
+    if (node.body) {
-    sb.push(" {\n");
+      sb.push(" ");
-    for (i = 0, k = node.statements.length; i < k; ++i) {
+      serializeStatement(node.body, sb);
-      serializeTerminatedStatement(node.statements[i], sb);
     }
-    sb.push("}");
   }
 }
 

src/parser.ts

@@ -79,7 +79,8 @@ import {
   addModifier,
   getModifier,
   hasModifier,
-  setReusableModifiers
+  setReusableModifiers,
+  FunctionExpression
 
 } from "./ast";
 
@@ -776,7 +777,8 @@ export class Parser extends DiagnosticEmitter {
   }
 
   parseParameter(
-    tn: Tokenizer
+    tn: Tokenizer,
+    suppressErrors: bool = false
   ): Parameter | null {
 
     // before: '...'? Identifier '?'? (':' Type)? ('=' Expression)?
@@ -927,10 +929,8 @@ export class Parser extends DiagnosticEmitter {
 
     var isDeclare = hasModifier(ModifierKind.DECLARE, modifiers);
 
-    var statements: Statement[] | null = null;
+    var body: Statement | null = null;
     if (tn.skip(Token.OPENBRACE)) {
-      statements = new Array();
-
       if (isDeclare) {
         this.error(
           DiagnosticCode.An_implementation_cannot_be_declared_in_ambient_contexts,
@@ -938,12 +938,8 @@ export class Parser extends DiagnosticEmitter {
         ); // recoverable
       }
 
-      while (!tn.skip(Token.CLOSEBRACE)) {
+      body = this.parseBlockStatement(tn, false);
-        var statement = this.parseStatement(tn);
+      if (!body) return null;
-        if (!statement) return null;
-        statements.push(<Statement>statement);
-      }
-
     } else if (!isDeclare) {
       this.error(
         DiagnosticCode.Function_implementation_is_missing_or_not_immediately_following_the_declaration,
@@ -956,7 +952,7 @@ export class Parser extends DiagnosticEmitter {
       typeParameters,
       <Parameter[]>parameters,
       returnType,
-      statements,
+      body,
       modifiers,
       decorators,
       tn.range(startPos, tn.pos)
@@ -965,6 +961,102 @@ export class Parser extends DiagnosticEmitter {
     return ret;
   }
 
+  parseFunctionExpression(tn: Tokenizer): FunctionExpression | null {
+    var startPos = tn.tokenPos;
+    var identifier: IdentifierExpression;
+    var isArrow = false;
+
+    // either at 'function':
+    //  Identifier?
+    //  '(' Parameters (':' Type)?
+    //  Statement
+
+    if (tn.token == Token.FUNCTION) {
+      isArrow = false;
+      if (tn.skip(Token.IDENTIFIER)) {
+        identifier = Node.createIdentifierExpression(tn.readIdentifier(), tn.range());
+      } else { // empty name
+        identifier = Node.createIdentifierExpression("", tn.range(tn.pos, tn.pos));
+      }
+      if (!tn.skip(Token.OPENPAREN)) {
+        this.error(
+          DiagnosticCode._0_expected,
+          tn.range(tn.pos), "("
+        );
+        return null;
+      }
+
+    // or at '(' of arrow function:
+    //  Parameters (':' Type)?
+    //  Statement
+
+    } else {
+      isArrow = true;
+      assert(tn.token == Token.OPENPAREN);
+      identifier = Node.createIdentifierExpression("", tn.range(tn.tokenPos, tn.tokenPos));
+    }
+
+    // TODO: type parameters? doesn't seem worth it.
+
+    var parameters = this.parseParameters(tn);
+    if (!parameters) return null;
+
+    return this.parseFunctionExpressionCommon(tn, identifier, parameters, isArrow, startPos);
+  }
+
+  private parseFunctionExpressionCommon(
+    tn: Tokenizer,
+    identifier: IdentifierExpression,
+    parameters: Parameter[],
+    isArrow: bool,
+    startPos: i32 = -1
+  ): FunctionExpression | null {
+    if (startPos < 0) startPos = identifier.range.start;
+
+    var returnType: TypeNode | null = null;
+    if (tn.skip(Token.COLON)) {
+      returnType = this.parseType(tn);
+      if (!returnType) return null;
+    }
+
+    if (isArrow) {
+      if (!tn.skip(Token.EQUALS_GREATERTHAN)) {
+        this.error(
+          DiagnosticCode._0_expected,
+          tn.range(tn.pos), "=>"
+        );
+        return null;
+      }
+    }
+
+    var body: Statement | null;
+    if (isArrow) {
+      body = this.parseStatement(tn, false);
+    } else {
+      if (!tn.skip(Token.OPENBRACE)) {
+        this.error(
+          DiagnosticCode._0_expected,
+          tn.range(tn.pos), "{"
+        );
+        return null;
+      }
+      body = this.parseBlockStatement(tn, false);
+    }
+    if (!body) return null;
+
+    var declaration = Node.createFunctionDeclaration(
+      identifier,
+      [],
+      parameters,
+      returnType,
+      body,
+      null,
+      null,
+      tn.range(startPos, tn.pos)
+    );
+    return Node.createFunctionExpression(declaration, isArrow);
+  }
+
   parseClass(
     tn: Tokenizer,
     modifiers: Modifier[] | null,
@@ -1184,7 +1276,7 @@ export class Parser extends DiagnosticEmitter {
           ); // recoverable
         }
 
-        var statements: Statement[] | null = null;
+        var body: Statement | null = null;
         if (tn.skip(Token.OPENBRACE)) {
           if (parentIsDeclare) {
             this.error(
@@ -1192,12 +1284,8 @@ export class Parser extends DiagnosticEmitter {
               tn.range()
             ); // recoverable
           }
-          statements = new Array();
+          body = this.parseBlockStatement(tn, false);
-          while (!tn.skip(Token.CLOSEBRACE)) {
+          if (!body) return null;
-            var statement = this.parseStatement(tn);
-            if (!statement) return null;
-            statements.push(<Statement>statement);
-          }
         } else if (!parentIsDeclare) {
           this.error(
             DiagnosticCode.Function_implementation_is_missing_or_not_immediately_following_the_declaration,
@@ -1210,7 +1298,7 @@ export class Parser extends DiagnosticEmitter {
           typeParameters,
           parameters,
           returnType,
-          statements,
+          body,
           modifiers,
           decorators,
           tn.range(startPos, tn.pos)
@@ -2212,7 +2300,68 @@ export class Parser extends DiagnosticEmitter {
     switch (token) {
 
       // ParenthesizedExpression
+      // FunctionExpression
       case Token.OPENPAREN:
+
+        // determine whether this is a function expression
+        if (tn.skip(Token.CLOSEPAREN)) { // must be a function expression (fast route)
+          return this.parseFunctionExpressionCommon(
+            tn,
+            Node.createIdentifierExpression("", tn.range(startPos, startPos)),
+            [],
+            true
+          );
+        }
+        tn.mark();
+        var again = true;
+        do {
+          switch (tn.next(true)) {
+
+            // function expression
+            case Token.DOT_DOT_DOT:
+              tn.reset();
+              return this.parseFunctionExpression(tn);
+
+            // can be both
+            case Token.IDENTIFIER:
+              tn.readIdentifier();
+              switch (tn.next()) {
+
+                // if we got here, check for arrow
+                case Token.CLOSEPAREN:
+                  if (!tn.skip(Token.EQUALS_GREATERTHAN)) {
+                    again = false;
+                    break;
+                  }
+                  // fall-through
+
+                // function expression
+                case Token.QUESTION:   // optional parameter
+                case Token.COLON:      // type annotation
+                  tn.reset();
+                  return this.parseFunctionExpression(tn);
+
+                // can be both
+                case Token.COMMA:
+                  break; // continue
+
+                // parenthesized expression
+                // case Token.EQUALS:  // missing type annotation for simplicity
+                default:
+                  again = false;
+                  break;
+              }
+              break;
+
+            // parenthesized expression
+            default:
+              again = false;
+              break;
+          }
+        } while (again);
+        tn.reset();
+
+        // parse parenthesized
         expr = this.parseExpression(tn);
         if (!expr) return null;
         if (!tn.skip(Token.CLOSEPAREN)) {
@@ -2307,6 +2456,9 @@ export class Parser extends DiagnosticEmitter {
           tn.range(startPos, tn.pos)
         );
 
+      case Token.FUNCTION:
+        return this.parseFunctionExpression(tn);
+
       default:
         this.error(
           DiagnosticCode.Expression_expected,

tests/parser/function-expression.ts

@@ -0,0 +1,16 @@
+var a = function(): void {
+  ;
+};
+var b = function someName(): void {
+  ;
+};
+var c = function(a: i32, b: i32): i32 {
+  ;
+};
+var d = (): void => {
+  ;
+};
+var e = (a: i32, b: i32): i32 => {
+  ;
+};
+var f = (a: i32): i32 => a;

tests/parser/function-expression.ts.fixture.ts

@@ -0,0 +1,16 @@
+var a = function(): void {
+;
+};
+var b = function someName(): void {
+;
+};
+var c = function(a: i32, b: i32): i32 {
+;
+};
+var d = (): void => {
+;
+};
+var e = (a: i32, b: i32): i32 => {
+;
+};
+var f = (a: i32): i32 => a;