Add function calling syntax

6 files changed, 100 insertions, 26 deletions

diff --git a/src/com/craftinginterpreters/lox/AstPrinter.java b/src/com/craftinginterpreters/lox/AstPrinter.java
index 65f1916..4c120d3 100644
--- a/src/com/craftinginterpreters/lox/AstPrinter.java
+++ b/src/com/craftinginterpreters/lox/AstPrinter.java
@@ -11,13 +11,23 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
     }
 
     @Override
+    public String visitCallExpr(Expr.Call expr) {
+        StringBuilder builder = new StringBuilder();
+
+        builder.append(print(expr.callee));
+        builder.append(parenthesizeExpr("", expr.arguments));
+
+        return builder.toString();
+    }
+
+    @Override
     public String visitBinaryExpr(Expr.Binary expr) {
-        return parenthesize(expr.operator.lexeme, expr.left, expr.right);
+        return parenthesizeExpr(expr.operator.lexeme, expr.left, expr.right);
     }
 
     @Override
     public String visitGroupingExpr(Expr.Grouping expr) {
-        return parenthesize("group", expr.expression);
+        return parenthesizeExpr("group", expr.expression);
     }
 
     @Override
@@ -29,12 +39,12 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
 
     @Override
     public String visitLogicalExpr(Expr.Logical expr) {
-        return parenthesize(expr.operator.type.toString(), expr.left, expr.right);
+        return parenthesizeExpr(expr.operator.type.toString(), expr.left, expr.right);
     }
 
     @Override
     public String visitUnaryExpr(Expr.Unary expr) {
-        return parenthesize(expr.operator.lexeme, expr.right);
+        return parenthesizeExpr(expr.operator.lexeme, expr.right);
     }
 
     @Override
@@ -44,12 +54,12 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
 
     @Override
     public String visitAssignExpr(Expr.Assign expression) {
-        return parenthesize(expression.name.lexeme + " = ", expression.value);
+        return parenthesizeExpr(expression.name.lexeme + " = ", expression.value);
     }
 
     @Override
     public String visitVarStmt(Stmt.Var statement) {
-        return parenthesize("define " + statement.name.lexeme + " = ", statement.initializer);
+        return parenthesizeExpr("define " + statement.name.lexeme + " = ", statement.initializer);
     }
 
     @Override
@@ -57,8 +67,8 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
         StringBuilder builder = new StringBuilder();
 
         builder.append('(');
-        builder.append(parenthesize("while", statement.condition));
-        builder.append(parenthesize("do", statement.body));
+        builder.append(parenthesizeExpr("while", statement.condition));
+        builder.append(parenthesizeStmt("do", statement.body));
         builder.append(')');
 
         return builder.toString();
@@ -66,7 +76,7 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
 
     @Override
     public String visitPrintStmt(Stmt.Print statement) {
-        return parenthesize("print", statement.expression);
+        return parenthesizeExpr("print", statement.expression);
     }
 
     @Override
@@ -79,21 +89,25 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
         StringBuilder builder = new StringBuilder();
 
         builder.append("(");
-        builder.append(parenthesize("if", stmt.condition));
-        builder.append(parenthesize("then", stmt.thenBranch));
+        builder.append(parenthesizeExpr("if", stmt.condition));
+        builder.append(parenthesizeStmt("then", stmt.thenBranch));
 
         if (stmt.elseBranch != null) {
-            builder.append(parenthesize("else", stmt.elseBranch));
+            builder.append(parenthesizeStmt("else", stmt.elseBranch));
         }
         return builder.toString();
     }
 
     @Override
     public String visitBlockStmt(Stmt.Block block) {
-        return parenthesize("", block.statements);
+        return parenthesizeStmt("", block.statements);
+    }
+
+    private String parenthesizeExpr(String name, Expr... exprs) {
+        return parenthesizeExpr(name, exprs);
     }
 
-    private String parenthesize(String name, Expr... exprs) {
+    private String parenthesizeExpr(String name, List<Expr> exprs) {
         StringBuilder builder = new StringBuilder();
 
         builder.append("(").append(name);
@@ -106,7 +120,7 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
         return builder.toString();
     }
 
-    private String parenthesize(String name, List<Stmt> statements) {
+    private String parenthesizeStmt(String name, List<Stmt> statements) {
         StringBuilder builder = new StringBuilder();
 
         builder.append("(").append(name);
@@ -119,8 +133,8 @@ class AstPrinter implements Expr.Visitor<String>, Stmt.Visitor<String> {
         return builder.toString();
     }
 
-    private String parenthesize(String name, Stmt... statements) {
-        return parenthesize(name, statements);
+    private String parenthesizeStmt(String name, Stmt... statements) {
+        return parenthesizeStmt(name, statements);
     }
 
     public static void main(String[] args) {
diff --git a/src/com/craftinginterpreters/lox/CMakeLists.txt b/src/com/craftinginterpreters/lox/CMakeLists.txt
index 447b2cf..b437b7a 100644
--- a/src/com/craftinginterpreters/lox/CMakeLists.txt
+++ b/src/com/craftinginterpreters/lox/CMakeLists.txt
@@ -20,4 +20,5 @@ add_jar(Lox
   Interpreter.java
   RuntimeError.java
   Environment.java
+  LoxCallable.java
   ENTRY_POINT com/craftinginterpreters/lox/Lox)
diff --git a/src/com/craftinginterpreters/lox/Interpreter.java b/src/com/craftinginterpreters/lox/Interpreter.java
index 9d0cfb3..f752e77 100644
--- a/src/com/craftinginterpreters/lox/Interpreter.java
+++ b/src/com/craftinginterpreters/lox/Interpreter.java
@@ -1,5 +1,6 @@
 package com.craftinginterpreters.lox;
 
+import java.util.ArrayList;
 import java.util.List;
 
 class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
@@ -222,6 +223,27 @@ class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
         return null;
     }
 
+    @Override
+    public Object visitCallExpr(Expr.Call expr) {
+        Object callee = evaluate(expr.callee);
+
+        List<Object> arguments = new ArrayList<>();
+        for (Expr argument : expr.arguments) {
+            arguments.add(evaluate(argument));
+        }
+
+        if (!(callee instanceof LoxCallable)) {
+            throw new RuntimeError(expr.paren, "Can only call functions and classes.");
+        }
+
+        LoxCallable function = (LoxCallable) callee;
+        if (arguments.size() != function.arity()) {
+            throw new RuntimeError(expr.paren, "Expected " + function.arity() + " arguments but got " + arguments.size() + ".");
+        }
+
+        return function.call(this, arguments);
+    }
+
     public void interpret(List<Stmt> statements) {
         try {
             for (Stmt statement : statements) {
diff --git a/src/com/craftinginterpreters/lox/LoxCallable.java b/src/com/craftinginterpreters/lox/LoxCallable.java
new file mode 100644
index 0000000..4204c20
--- /dev/null
+++ b/src/com/craftinginterpreters/lox/LoxCallable.java
@@ -0,0 +1,9 @@
+package com.craftinginterpreters.lox;
+
+import java.util.List;
+
+interface LoxCallable {
+    int arity();
+
+    Object call(Interpreter interpreter, List<Object> arguments);
+}
diff --git a/src/com/craftinginterpreters/lox/Parser.java b/src/com/craftinginterpreters/lox/Parser.java
index 7d7b27a..df3ce3f 100644
--- a/src/com/craftinginterpreters/lox/Parser.java
+++ b/src/com/craftinginterpreters/lox/Parser.java
@@ -84,13 +84,11 @@ class Parser {
         Stmt body = statement();
 
         if (increment != null) {
-            body = new Stmt.Block(
-                                  Arrays.asList(
-                                                body,
-                            new Stmt.Expression(increment)));
+            body = new Stmt.Block(Arrays.asList(body, new Stmt.Expression(increment)));
         }
 
-        if (condition == null) condition = new Expr.Literal(true);
+        if (condition == null)
+            condition = new Expr.Literal(true);
         body = new Stmt.While(condition, body);
 
         if (initializer != null) {
@@ -255,7 +253,37 @@ class Parser {
             return new Expr.Unary(operator, right);
         }
 
-        return primary();
+        return call();
+    }
+
+    private Expr finishCall(Expr callee) {
+        List<Expr> arguments = new ArrayList<>();
+        if (!check(RIGHT_PAREN)) {
+            do {
+                if (arguments.size() >= 255) {
+                    error(peek(), "Can't have more than 255 arguments.");
+                }
+                arguments.add(expression());
+            } while (match(COMMA));
+        }
+
+        Token paren = consume(RIGHT_PAREN, "Expect ')' after arguments.");
+
+        return new Expr.Call(callee, paren, arguments);
+    }
+
+    private Expr call() {
+        Expr expr = primary();
+
+        while (true) {
+            if (match(LEFT_PAREN)) {
+                expr = finishCall(expr);
+            } else {
+                break;
+            }
+        }
+
+        return expr;
     }
 
     private Expr primary() {
diff --git a/src/com/craftinginterpreters/tool/GenerateAst.java b/src/com/craftinginterpreters/tool/GenerateAst.java
index 8845c6e..8c063bf 100644
--- a/src/com/craftinginterpreters/tool/GenerateAst.java
+++ b/src/com/craftinginterpreters/tool/GenerateAst.java
@@ -16,9 +16,9 @@ public class GenerateAst {
 
         defineAst(outputDir, "Expr",
                 Arrays.asList("Assign : Token name, Expr value", "Binary : Expr left, Token operator, Expr right",
-                        "Grouping : Expr expression", "Literal : Object value",
-                        "Logical : Expr left, Token operator, Expr right", "Unary : Token operator, Expr right",
-                        "Variable : Token name"));
+                        "Call : Expr callee, Token paren, List<Expr> arguments", "Grouping : Expr expression",
+                        "Literal : Object value", "Logical : Expr left, Token operator, Expr right",
+                        "Unary : Token operator, Expr right", "Variable : Token name"));
         defineAst(outputDir, "Stmt",
                 Arrays.asList("Block : List<Stmt> statements", "Expression : Expr expression",
                         "If : Expr condition, Stmt thenBranch, Stmt elseBranch", "Print : Expr expression",