✨ Parse call expressions

ast/ast.go

@@ -80,6 +80,12 @@ type (
 		Operator token.Token // operator token
 		Right    Expression  // right operand
 	}
+
+	CallExpression struct {
+		Pos      token.Pos    // Position of the identifier being called
+		Function Expression   // Function being called
+		Args     []Expression // Comma-separated list of arguments
+	}
 )
 
 // Start() and End() implementations for Expression type Nodes
@@ -107,6 +113,13 @@ func (x *InfixExpression) Start() token.Pos { return x.Pos }
 func (x *InfixExpression) End() token.Pos {
 	return x.Right.End()
 }
+func (x *CallExpression) Start() token.Pos { return x.Pos }
+func (x *CallExpression) End() token.Pos {
+	if len(x.Args) > 0 {
+		return x.Args[len(x.Args)-1].End() + 1 // @TODO: Shouldnt +2?
+	}
+	return x.Pos + 2 // length of "()"
+}
 
 // expressionNode() implementations to ensure that only expressions can be
 // assigned to an Expression. This is useful if by mistake we try to use
@@ -117,6 +130,7 @@ func (*NumberLiteral) expressionNode()    {}
 func (*BooleanLiteral) expressionNode()   {}
 func (*PrefixExpression) expressionNode() {}
 func (*InfixExpression) expressionNode()  {}
+func (*CallExpression) expressionNode()   {}
 
 // String() implementations for Expressions
 
@@ -147,6 +161,19 @@ func (x *InfixExpression) String() string {
 	out.WriteString(")")
 	return out.String()
 }
+func (x *CallExpression) String() string {
+	var out bytes.Buffer
+	out.WriteString(x.Function.String())
+	out.WriteString("(")
+	for i, arg := range x.Args {
+		if i > 0 {
+			out.WriteString(", ")
+		}
+		out.WriteString(arg.String())
+	}
+	out.WriteString(")")
+	return out.String()
+}
 
 /*~*~*~*~*~*~*~*~*~*~*~*~*~* Types ~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*/
 // Type nodes are constrains on expressions. They define the kinds of values

parser/exprparsing.go

@@ -114,6 +114,7 @@ var precedences = map[token.TokenType]int{
 	// 1.
 	// @TODO: The function calls, array subscripting, member access etc.
 	// is harder to implement.
+	token.LPAREN: HIGHEST,
 }
 
 func (p *Parser) peekPrecedence() int {
@@ -307,3 +308,49 @@ func (p *Parser) parseElementaryType() ast.Expression {
 
 	return et
 }
+
+// parseCallExpression is called when LPAREN is encountered in an
+// infix position. That's why we have access to the function ident
+// and we can pass it as an argument to the function.
+func (p *Parser) parseCallExpression(fn ast.Expression) ast.Expression {
+	if p.trace {
+		defer un(trace("parseCallExpression"))
+	}
+
+	callExp := &ast.CallExpression{
+		Pos:      fn.Start(), // TODO: fn is not passed as ref, will this work?
+		Function: fn,
+	}
+
+	callExp.Args = p.parseCallArguments()
+	return callExp
+}
+
+func (p *Parser) parseCallArguments() []ast.Expression {
+	if p.trace {
+		defer un(trace("parseCallArguments"))
+	}
+
+	args := []ast.Expression{}
+	if p.peekTkn.Type == token.RPAREN {
+		p.nextToken()
+		return args
+	}
+
+	// Move to the first arg.
+	p.nextToken()
+	args = append(args, p.parseExpression(LOWEST))
+
+	for p.peekTkn.Type == token.COMMA {
+		p.nextToken() // Sitting on comma
+		p.nextToken() // Move to the next arg
+
+		args = append(args, p.parseExpression(LOWEST))
+	}
+
+	if !p.expectPeek(token.RPAREN) {
+		return nil
+	}
+
+	return args
+}

parser/exprparsing_test.go

@@ -274,6 +274,40 @@ func Test_ParseOperatorPrecedence(t *testing.T) {
 	}
 }
 
+func Test_ParseCallExpression(t *testing.T) {
+	src := `function test() public {
+        foo(a + b, 3 * 5, bar);
+    }`
+
+	file := test_helper_parseSource(t, src, false)
+
+	fnBody := test_helper_parseFnBody(t, file)
+
+	if len(fnBody.Statements) != 1 {
+		t.Fatalf("Expected 1 statement, got %d", len(fnBody.Statements))
+	}
+
+	exprStmt, ok := fnBody.Statements[0].(*ast.ExpressionStatement)
+	if !ok {
+		t.Fatalf("Expected ExpressionStatement, got %T", fnBody.Statements[0])
+	}
+
+	callExpr, ok := exprStmt.Expression.(*ast.CallExpression)
+	if !ok {
+		t.Fatalf("Expected CallExpression, got %T", exprStmt.Expression)
+	}
+
+	test_Identifier(t, callExpr.Function, "foo")
+
+	if len(callExpr.Args) != 3 {
+		t.Fatalf("Expected 3 arguments, got %d", len(callExpr.Args))
+	}
+
+	test_InfixExpression(t, callExpr.Args[0], "a", "+", "b")
+	test_InfixExpression(t, callExpr.Args[1], big.NewInt(3), "*", big.NewInt(5))
+	test_LiteralExpression(t, callExpr.Args[2], "bar")
+}
+
 /*~*~*~*~*~*~*~*~*~*~*~*~* Helper Functions ~*~*~*~*~*~*~*~*~*~*~*~*~*/
 
 func test_helper_parseSource(t *testing.T, src string, tracing bool) *ast.File {

parser/parser.go

@@ -87,6 +87,8 @@ func (p *Parser) Init(file *token.File) {
 	p.registerInfix(token.ASSIGN_MUL, p.parseInfixExpression)
 	p.registerInfix(token.ASSIGN_DIV, p.parseInfixExpression)
 	p.registerInfix(token.ASSIGN_MOD, p.parseInfixExpression)
+
+	p.registerInfix(token.LPAREN, p.parseCallExpression)
 }
 
 func registerPrefixElementaryTypes(p *Parser) {