From ca46690f9166681e4b32af90e28fb215c12f76c0 Mon Sep 17 00:00:00 2001
From: Bobby <bobbyskhs@gmail.com>
Date: Wed, 10 Apr 2024 20:42:41 +0000
Subject: hashes

---
 parser/parser.go      |  30 +++++++++++++++
 parser/parser_test.go | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 134 insertions(+)

(limited to 'parser')

diff --git a/parser/parser.go b/parser/parser.go
index 4fa36b1..2de9e56 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -75,6 +75,7 @@ func New(l *lexer.Lexer) *Parser {
 	p.registerPrefix(tokens.LPAREN, p.parseGroupedExpression)
 	p.registerPrefix(tokens.STRING, p.parseStringLiteral)
 	p.registerPrefix(tokens.LBRACKET, p.parseArrayLiteral)
+	p.registerPrefix(tokens.LBRACE, p.parseHashLiteral)
 
 	// Initialize the infix parse functions.
 	p.infixParseFns = make(map[tokens.TokenType]infixParseFn)
@@ -494,6 +495,35 @@ func (p *Parser) parseIndexExpression(left ast.Expression) ast.Expression {
 	return exp
 }
 
+func (p *Parser) parseHashLiteral() ast.Expression {
+	hash := &ast.HashLiteral{Token: p.curToken}
+	hash.Pairs = make(map[ast.Expression]ast.Expression)
+
+	for !p.peekTokenIs(tokens.RBRACE) {
+		p.nextToken()
+		key := p.parseExpression(LOWEST)
+
+		if !p.expectPeek(tokens.COLON) {
+			return nil
+		}
+
+		p.nextToken()
+		value := p.parseExpression(LOWEST)
+
+		hash.Pairs[key] = value
+
+		if !p.peekTokenIs(tokens.RBRACE) && !p.expectPeek(tokens.COMMA) {
+			return nil
+		}
+	}
+
+	if !p.expectPeek(tokens.RBRACE) {
+		return nil
+	}
+
+	return hash
+}
+
 // curTokenIs returns true if the current token is of the given type.
 func (p *Parser) curTokenIs(t tokens.TokenType) bool {
 	return p.curToken.Type == t
diff --git a/parser/parser_test.go b/parser/parser_test.go
index 7b347f5..e38301a 100644
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@@ -859,3 +859,107 @@ func TestParsingIndexExpressions(t *testing.T) {
 		return
 	}
 }
+
+func TestParsingHashLiteralsStringKeys(t *testing.T) {
+	input := `{"one": 1, "two": 2, "three": 3}`
+
+	var l *lexer.Lexer = lexer.New(input)
+	var p *Parser = New(l)
+
+	var program *ast.Program = p.ParseProgram()
+	checkParserErrors(t, p)
+
+	stmt := program.Statements[0].(*ast.ExpressionStatement)
+	hash, ok := stmt.Expression.(*ast.HashLiteral)
+	if !ok {
+		t.Fatalf("exp is not ast.HashLiteral. got=%T", stmt.Expression)
+	}
+
+	if len(hash.Pairs) != 3 {
+		t.Errorf("hash.Pairs has wrong length. got=%d", len(hash.Pairs))
+	}
+
+	expected := map[string]int64{
+		"one":   1,
+		"two":   2,
+		"three": 3,
+	}
+
+	for key, value := range hash.Pairs {
+		literal, ok := key.(*ast.StringLiteral)
+		if !ok {
+			t.Errorf("key is not ast.StringLiteral. got=%T", key)
+		}
+
+		expectedValue := expected[literal.Value]
+		testIntegerLiteral(t, value, expectedValue)
+	}
+}
+
+func TestParsingEmptyHashLiteral(t *testing.T) {
+	input := `{}`
+
+	var l *lexer.Lexer = lexer.New(input)
+	var p *Parser = New(l)
+
+	var program *ast.Program = p.ParseProgram()
+	checkParserErrors(t, p)
+
+	stmt := program.Statements[0].(*ast.ExpressionStatement)
+	hash, ok := stmt.Expression.(*ast.HashLiteral)
+	if !ok {
+		t.Fatalf("exp is not ast.HashLiteral. got=%T", stmt.Expression)
+	}
+
+	if len(hash.Pairs) != 0 {
+		t.Errorf("hash.Pairs has wrong length. got=%d", len(hash.Pairs))
+	}
+}
+
+func TestParsingHashLiteralsWithExpressions(t *testing.T) {
+	input := `{"one": 0 + 1, "two": 10 - 8, "three": 15 / 5}`
+
+	var l *lexer.Lexer = lexer.New(input)
+	var p *Parser = New(l)
+
+	var program *ast.Program = p.ParseProgram()
+	checkParserErrors(t, p)
+
+	stmt := program.Statements[0].(*ast.ExpressionStatement)
+	hash, ok := stmt.Expression.(*ast.HashLiteral)
+	if !ok {
+		t.Fatalf("exp is not ast.HashLiteral. got=%T", stmt.Expression)
+	}
+
+	if len(hash.Pairs) != 3 {
+		t.Errorf("hash.Pairs has wrong length. got=%d", len(hash.Pairs))
+	}
+
+	tests := map[string]func(ast.Expression){
+		"one": func(e ast.Expression) {
+			testInfixExpression(t, e, 0, "+", 1)
+		},
+		"two": func(e ast.Expression) {
+			testInfixExpression(t, e, 10, "-", 8)
+		},
+		"three": func(e ast.Expression) {
+			testInfixExpression(t, e, 15, "/", 5)
+		},
+	}
+
+	for key, value := range hash.Pairs {
+		literal, ok := key.(*ast.StringLiteral)
+		if !ok {
+			t.Errorf("key is not ast.StringLiteral. got=%T", key)
+			continue
+		}
+
+		testFunc, ok := tests[literal.Value]
+		if !ok {
+			t.Errorf("no test function for key %q found", literal.Value)
+			continue
+		}
+
+		testFunc(value)
+	}
+}
-- 
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