Use semicolon as terminator and peek to add empty statement

README.md

@@ -36,7 +36,7 @@ npm run mtsc ./tests/singleVar.ts
 - [x] Add EmptyStatement (https://github.com/imteekay/mini-typescript/pull/2).
 - [x] Make semicolon a statement ender, not statement separator.
   - Hint: You'll need a predicate to peek at the next token and decide if it's the start of an element.
-  - Bonus: Switch from semicolon to newline as statement ender.
+  - [ ] Bonus: Switch from semicolon to newline as statement ender.
 - [x] Add string literals (https://github.com/imteekay/mini-typescript/pull/4).
 - [x] Refactor: rename `Literal` to `NumericLiteral` (https://github.com/imteekay/mini-typescript/pull/6).
 - [ ] Add let.

baselines/reference/emptyStatement.tree.baseline

@@ -46,9 +46,6 @@
         "kind": "NumericLiteral",
         "value": 2
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/redeclare.tree.baseline

@@ -29,9 +29,6 @@
         "kind": "NumericLiteral",
         "value": 2
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/singleIdentifier.tree.baseline

@@ -7,9 +7,6 @@
         "kind": "Identifier",
         "text": "x"
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/singleTypedVar.tree.baseline

@@ -44,9 +44,6 @@
         "value": "test",
         "isSingleQuote": true
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/singleVar.tree.baseline

@@ -18,9 +18,6 @@
         "kind": "NumericLiteral",
         "value": 1
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/stringLiteral.tree.baseline

@@ -145,9 +145,6 @@
         "value": "escaped\nR",
         "isSingleQuote": true
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/terminator.tree.baseline

@@ -73,9 +73,6 @@
         "kind": "Identifier",
         "text": "z"
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/twoStatements.tree.baseline

@@ -32,9 +32,6 @@
           "value": 2
         }
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/twoTypedStatements.tree.baseline

@@ -36,9 +36,6 @@
           "value": 2
         }
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

baselines/reference/typeAlias.tree.baseline

@@ -192,9 +192,6 @@
         "kind": "Identifier",
         "text": "Net"
       }
-    },
-    {
-      "kind": "EndOfFile"
     }
   ]
 }

src/check.ts

@@ -14,7 +14,6 @@ const stringType: Type = { id: 'string' };
 const numberType: Type = { id: 'number' };
 const errorType: Type = { id: 'error' };
 const empty: Type = { id: 'empty' };
-const eof: Type = { id: 'eof' };
 
 function typeToString(type: Type) {
   return type.id;
@@ -45,8 +44,6 @@ export function check(module: Module) {
         return checkType(statement.typename);
       case Node.EmptyStatement:
         return empty;
-      case Node.EndOfFile:
-        return eof;
     }
   }
 

src/emit.ts

@@ -34,8 +34,6 @@ function emitStatement(statement: Statement): string {
       return `type ${statement.name.text} = ${statement.typename.text}`;
     case Node.EmptyStatement:
       return '';
-    case Node.EndOfFile:
-      return '';
   }
 }
 

src/parse.ts

@@ -15,7 +15,11 @@ export function parse(lexer: Lexer): Module {
 
   function parseModule(): Module {
     return {
-      statements: parseStatements(parseStatement),
+      statements: parseStatements(
+        parseStatement,
+        () => tryParseToken(Token.Semicolon),
+        () => lexer.token() === Token.Semicolon,
+      ),
       locals: new Map(),
     };
   }
@@ -63,9 +67,7 @@ export function parse(lexer: Lexer): Module {
   function parseStatement(): Statement {
     const pos = lexer.pos();
 
-    if (tryParseToken(Token.EOF)) {
-      return { kind: Node.EndOfFile };
-    } else if (tryParseToken(Token.Var)) {
+    if (tryParseToken(Token.Var)) {
       const name = parseIdentifier();
       const typename = tryParseToken(Token.Colon)
         ? parseIdentifier()
@@ -78,13 +80,8 @@ export function parse(lexer: Lexer): Module {
       parseExpected(Token.Equals);
       const typename = parseIdentifier();
       return { kind: Node.TypeAlias, name, typename, pos };
-    } else if (tryParseToken(Token.Semicolon)) {
-      // if a semicolon is followed by another semicolon,
-      // it should return an empty statement
-      if (lexer.token() === Token.Semicolon) {
-        return { kind: Node.EmptyStatement };
-      }
-      return parseStatement();
+    } else if (lexer.token() === Token.Semicolon) {
+      return { kind: Node.EmptyStatement };
     }
     return { kind: Node.ExpressionStatement, expr: parseExpression(), pos };
   }
@@ -108,10 +105,18 @@ export function parse(lexer: Lexer): Module {
     }
   }
 
-  function parseStatements<T>(element: () => T) {
+  function parseStatements<T>(
+    element: () => T,
+    terminator: () => boolean,
+    peek: () => boolean,
+  ) {
     const list = [element()];
     while (lexer.token() !== Token.EOF) {
-      list.push(element());
+      if (terminator()) {
+        if (peek()) list.push(element());
+      } else {
+        list.push(element());
+      }
     }
     return list;
   }

src/transform.ts

@@ -18,8 +18,6 @@ function typescript(statements: Statement[]) {
         return [];
       case Node.EmptyStatement:
         return [];
-      case Node.EndOfFile:
-        return [];
     }
   }
 }

src/types.ts

@@ -73,12 +73,7 @@ export type Assignment = Location & {
   value: Expression;
 };
 
-export type Statement =
-  | ExpressionStatement
-  | Var
-  | TypeAlias
-  | EmptyStatement
-  | EndOfFile;
+export type Statement = ExpressionStatement | Var | TypeAlias | EmptyStatement;
 
 export type ExpressionStatement = Location & {
   kind: Node.ExpressionStatement;
@@ -102,10 +97,6 @@ export type EmptyStatement = {
   kind: Node.EmptyStatement;
 };
 
-export type EndOfFile = {
-  kind: Node.EndOfFile;
-};
-
 export type Declaration = Var | TypeAlias; // plus others, like function
 
 export type Symbol = {