golox/parser/parser_test.go

package parser

import (
	"golox/ast"
	"golox/errors"
	"golox/token"
	"testing"
)

func TestExpressionParsing(t *testing.T) {
	tests := []struct {
		name     string
		tokens   []token.Token
		expected string
	}{
		{
			name: "Simple expression",
			tokens: []token.Token{
				{Type: token.NUMBER, Literal: 1},
				{Type: token.PLUS, Lexeme: "+"},
				{Type: token.NUMBER, Literal: 2},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(+ 1 2)",
		},
		{
			name: "Unary expression",
			tokens: []token.Token{
				{Type: token.MINUS, Lexeme: "-"},
				{Type: token.NUMBER, Literal: 123},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(- 123)",
		},
		{
			name: "Grouping expression",
			tokens: []token.Token{
				{Type: token.LEFT_PAREN, Lexeme: "("},
				{Type: token.NUMBER, Literal: 1},
				{Type: token.PLUS, Lexeme: "+"},
				{Type: token.NUMBER, Literal: 2},
				{Type: token.RIGHT_PAREN, Lexeme: ")"},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(group (+ 1 2))",
		},
		{
			name: "Comparison expression",
			tokens: []token.Token{
				{Type: token.NUMBER, Literal: 1},
				{Type: token.GREATER, Lexeme: ">"},
				{Type: token.NUMBER, Literal: 2},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(> 1 2)",
		},
		{
			name: "Equality expression",
			tokens: []token.Token{
				{Type: token.NUMBER, Literal: 1},
				{Type: token.EQUAL_EQUAL, Lexeme: "=="},
				{Type: token.NUMBER, Literal: 2},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(== 1 2)",
		},
		{
			name: "Parsing error - missing right parenthesis",
			tokens: []token.Token{
				{Type: token.LEFT_PAREN, Lexeme: "("},
				{Type: token.NUMBER, Literal: 1},
				{Type: token.PLUS, Lexeme: "+"},
				{Type: token.NUMBER, Literal: 2},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "Expect ')' after expression.",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			parser := New(tt.tokens, errors.NewMockErrorLogger())
			stmts := parser.Parse()
			if len(stmts) != 1 {
				t.Fatalf("expected 1 statement, got %d", len(stmts))
			}

			stmt := stmts[0]
			var expr ast.Expr
			if es, ok := stmt.(*ast.ExpressionStmt); !ok {
				t.Errorf("expected ExprStmt, got %T", stmt)
			} else {
				expr = es.Expression
			}

			ap := ast.NewPrinter()
			s := ap.PrintExpr(expr)
			if s != tt.expected {
				t.Errorf("expected %v, got %v", tt.expected, s)
			}
		})
	}
}

func TestParseExpressionStmt(t *testing.T) {
	tests := []struct {
		name     string
		tokens   []token.Token
		expected string
	}{
		{
			name: "simple expression statement",
			tokens: []token.Token{
				{Type: token.NUMBER, Lexeme: "42", Literal: 42},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "42\n",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			parser := New(tt.tokens, errors.NewMockErrorLogger())
			stmts := parser.Parse()
			if len(stmts) != 1 {
				t.Fatalf("expected 1 statement, got %d", len(stmts))
			}

			ap := ast.NewPrinter()
			s := ap.PrintStmts(stmts)
			if s != tt.expected {
				t.Errorf("expected %v, got %v", tt.expected, s)
			}
		})
	}
}

func TestParsePrintStmt(t *testing.T) {
	tests := []struct {
		name     string
		tokens   []token.Token
		expected string
	}{
		{
			name: "simple print statement",
			tokens: []token.Token{
				{Type: token.PRINT, Lexeme: "print"},
				{Type: token.NUMBER, Lexeme: "42", Literal: 42},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(print 42)\n",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			parser := New(tt.tokens, errors.NewMockErrorLogger())
			stmts := parser.Parse()
			if len(stmts) != 1 {
				t.Fatalf("expected 1 statement, got %d", len(stmts))
			}

			ap := ast.NewPrinter()
			s := ap.PrintStmts(stmts)
			if s != tt.expected {
				t.Errorf("expected %v, got %v", tt.expected, s)
			}
		})
	}
}

func TestParseVarStmt(t *testing.T) {
	tests := []struct {
		name     string
		tokens   []token.Token
		expected string
	}{
		{
			name: "simple var statement",
			tokens: []token.Token{
				{Type: token.VAR, Lexeme: "var"},
				{Type: token.IDENTIFIER, Lexeme: "foo"},
				{Type: token.EQUAL, Lexeme: "="},
				{Type: token.NUMBER, Lexeme: "42", Literal: 42},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(var foo 42)\n",
		},
		{
			name: "simple var statement",
			tokens: []token.Token{
				{Type: token.VAR, Lexeme: "var"},
				{Type: token.IDENTIFIER, Lexeme: "foo"},
				{Type: token.SEMICOLON, Lexeme: ";"},
				{Type: token.EOF},
			},
			expected: "(var foo)\n",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			parser := New(tt.tokens, errors.NewMockErrorLogger())
			stmts := parser.Parse()
			if len(stmts) != 1 {
				t.Fatalf("expected 1 statement, got %d", len(stmts))
			}

			ap := ast.NewPrinter()
			s := ap.PrintStmts(stmts)
			if s != tt.expected {
				t.Errorf("expected %v, got %v", tt.expected, s)
			}
		})
	}
}