optimizations

internal/parser/parser.go

@@ -82,6 +82,7 @@ func New(fn string, l *lexer.Lexer) *Parser {
 	p.prefixParseFns = make(map[token.TokenType]prefixParseFn)
 	p.registerPrefix(token.IDENT, p.parseIdentifier)
 	p.registerPrefix(token.INT, p.parseIntegerLiteral)
+	p.registerPrefix(token.FLOAT, p.parseFloatLiteral)
 	p.registerPrefix(token.MINUS, p.parsePrefixExpression)
 	p.registerPrefix(token.TRUE, p.parseBoolean)
 	p.registerPrefix(token.FALSE, p.parseBoolean)
@@ -622,6 +623,21 @@ func (p *Parser) parseImportExpression() ast.Expression {
 	return expression
 }
 
+func (p *Parser) parseFloatLiteral() ast.Expression {
+	lit := &ast.FloatLiteral{Token: p.curToken}
+
+	value, err := strconv.ParseFloat(p.curToken.Literal, 64)
+	if err != nil {
+		msg := fmt.Sprintf("could not parse %q as float", p.curToken.Literal)
+		p.errors = append(p.errors, msg)
+		return nil
+	}
+
+	lit.Value = value
+
+	return lit
+}
+
 // Parse parses the input source into a top-level AST for either evaluation
 // or compilation to bytecode. The parameter fn denotes the filename the source
 // originated from.

internal/parser/parser_test.go

@@ -126,6 +126,37 @@ func TestIntegerLiteralExpression(t *testing.T) {
 	}
 }
 
+func TestFloatLiteralExpression(t *testing.T) {
+	input := "2.5;"
+
+	l := lexer.New(input)
+	p := New("<test>", l)
+	program := p.ParseProgram()
+	checkParserErrors(t, p)
+
+	if len(program.Statements) != 1 {
+		t.Fatalf("program has not enough statements. got=%d",
+			len(program.Statements))
+	}
+	stmt, ok := program.Statements[0].(*ast.ExpressionStatement)
+	if !ok {
+		t.Fatalf("program.Statements[0] is not ast.ExpressionStatement. got=%T",
+			program.Statements[0])
+	}
+
+	literal, ok := stmt.Expression.(*ast.FloatLiteral)
+	if !ok {
+		t.Fatalf("exp not *ast.FloatLiteral. got=%T", stmt.Expression)
+	}
+	if literal.Value != 2.5 {
+		t.Errorf("literal.Value not %f. got=%f", 2.5, literal.Value)
+	}
+	if literal.TokenLiteral() != "2.5" {
+		t.Errorf("literal.TokenLiteral not %s. got=%s", "2.5",
+			literal.TokenLiteral())
+	}
+}
+
 func TestParsingPrefixExpressions(t *testing.T) {
 	prefixTests := []struct {
 		input    string