1 files changed, 74 insertions, 3 deletions
diff --git a/parser/parser.go b/parser/parser.go
index 5840f0a..936d58a 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -1,25 +1,38 @@
 package parser
 
 import (
+	"fmt"
+
 	"github.com/mewsen/interpreter/ast"
 	"github.com/mewsen/interpreter/lexer"
 	"github.com/mewsen/interpreter/token"
 )
 
 type Parser struct {
-	l *lexer.Lexer
+	l      *lexer.Lexer
+	errors []string
 
 	curToken  token.Token
 	peekToken token.Token
 }
 
+func (p *Parser) peekError(t token.TokenType) {
+	msg := fmt.Sprintf("expected next token to be %s, got %s instead",
+		t, p.peekToken.Type)
+	p.errors = append(p.errors, msg)
+}
+
 func (p *Parser) NextToken() {
 	p.curToken = p.peekToken
 	p.peekToken = p.l.NextToken()
 }
 
+func (p *Parser) Errors() []string {
+	return p.errors
+}
+
 func New(l *lexer.Lexer) *Parser {
-	p := &Parser{l: l}
+	p := &Parser{l: l, errors: []string{}}
 
 	p.NextToken()
 	p.NextToken()
@@ -28,5 +41,63 @@ func New(l *lexer.Lexer) *Parser {
 }
 
 func (p *Parser) ParseProgram() *ast.Program {
-	return nil
+	program := &ast.Program{}
+	program.Statements = []ast.Statement{}
+
+	for p.curToken.Type != token.EOF {
+		stmt := p.parseStatement()
+		if stmt != nil {
+			program.Statements = append(program.Statements, stmt)
+		}
+		p.NextToken()
+	}
+
+	return program
+}
+
+func (p *Parser) parseStatement() ast.Statement {
+	switch p.curToken.Type {
+	case token.LET:
+		return p.parseLetStatement()
+	default:
+		return nil
+	}
+}
+
+func (p *Parser) parseLetStatement() *ast.LetStatement {
+	stmt := &ast.LetStatement{Token: p.curToken}
+
+	if !p.expectPeek(token.IDENT) {
+		return nil
+	}
+
+	stmt.Name = &ast.Identifier{Token: p.curToken, Value: p.curToken.Literal}
+
+	if !p.expectPeek(token.ASSIGN) {
+		return nil
+	}
+
+	// TODO: We're skipping the expressions until we encounter a semicolon
+	for !p.curTokenIs(token.SEMICOLON) {
+		p.NextToken()
+	}
+
+	return stmt
+}
+
+func (p *Parser) curTokenIs(t token.TokenType) bool {
+	return p.curToken.Type == t
+}
+
+func (p *Parser) peekTokenIs(t token.TokenType) bool {
+	return p.peekToken.Type == t
+}
+
+func (p *Parser) expectPeek(t token.TokenType) bool {
+	if p.peekTokenIs(t) {
+		p.NextToken()
+		return true
+	} else {
+		return false
+	}
 }