Added AST and parser support for types on variable declarations

DavidTimms · Jul 12, 2020 · 8f78320 · 8f78320
1 parent 2fc046c
commit 8f78320
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Showing 4 changed files with 23 additions and 11 deletions.
diff --git a/src/Parser.ts b/src/Parser.ts
@@ -210,11 +210,13 @@ export default class Parser {
     private varDeclaration(): Stmt {
         const name = this.consume("IDENTIFIER", "Expect variable name.");
 
+        const type = this.match("COLON") ? this.typeExpr() : null;
+
         const initializer = this.match("EQUAL") ? this.expression() : null;
 
         this.consume("SEMICOLON", "Expect ';' after variable declaration");
 
-        return new VarStmt(name, initializer);
+        return new VarStmt(name, type, initializer);
     }
 
     private whileStatement(): Stmt {

diff --git a/src/Stmt.ts b/src/Stmt.ts
@@ -87,6 +87,7 @@ export class ReturnStmt {
 export class VarStmt {
     constructor(
         readonly name: Token,
+        readonly type: TypeExpr | null,
         readonly initializer: Expr | null,
     ) {}
 

diff --git a/src/tool/generateAst.ts b/src/tool/generateAst.ts
@@ -35,17 +35,25 @@ function main(args: string[]): void {
 
     defineAst(outputDir, "Stmt", [
         "Block      -> statements: Stmt[]",
-        "Class      -> name: Token, superclass: VariableExpr | null, " +
-        "              methods: FunctionStmt[]",
+        `Class      -> name: Token,
+                       superclass: VariableExpr | null,
+                       methods: FunctionStmt[]`,
         "Expression -> expression: Expr",
-        "Function   -> name: Token, params: Parameter[], " +
-        "              returnType: TypeExpr | null, body: Stmt[]",
-        "If         -> condition: Expr, thenBranch: Stmt, " +
-        "              elseBranch: Stmt | null",
+        `Function   -> name: Token,
+                       params: Parameter[],
+                       returnType: TypeExpr | null,
+                       body: Stmt[]`,
+        `If         -> condition: Expr,
+                       thenBranch: Stmt,
+                       elseBranch: Stmt | null`,
         "Print      -> expression: Expr",
-        "Return     -> keyword: Token, value: Expr | null",
-        "Var        -> name: Token, initializer: Expr | null",
-        "While      -> condition: Expr, body: Stmt",
+        `Return     -> keyword: Token,
+                       value: Expr | null`,
+        `Var        -> name: Token,
+                       type: TypeExpr | null,
+                       initializer: Expr | null`,
+        `While      -> condition: Expr,
+                       body: Stmt`,
     ]);
 
     defineAst(outputDir, "TypeExpr", [
@@ -134,7 +142,7 @@ function parseClassDefinition(
 ): ClassDefinition {
     const [classPrefix, fieldList] = definition.split("->").map(s => s.trim());
     const className = classPrefix + baseName;
-    const fields = fieldList.split(", ").map(field => {
+    const fields = fieldList.split(",").map(field => {
         const [name, typeList] = field.split(":").map(s => s.trim());
         return {name, types: typeList.split("|").map(s => s.trim())};
     });

diff --git a/tests/variablesAndScope/variableWithType.lox b/tests/variablesAndScope/variableWithType.lox
@@ -0,0 +1 @@
+var x: Number = 123;