From 88a76bb57b07cb15e546f787d4a63dad75106c10 Mon Sep 17 00:00:00 2001
From: Michael Tews <git@tews.dev>
Date: Wed, 19 Jun 2024 06:07:54 +0200
Subject: feat(lexer): added new tokens

added == and !=
---
 ast/ast.go         | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 lexer/repl/repl.go | 31 +++++++++++++++++++++++++++++++
 main.go            | 11 +++++++++++
 parser/parser.go   | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 122 insertions(+)
 create mode 100644 ast/ast.go
 create mode 100644 lexer/repl/repl.go
 create mode 100644 main.go
 create mode 100644 parser/parser.go

diff --git a/ast/ast.go b/ast/ast.go
new file mode 100644
index 0000000..033005f
--- /dev/null
+++ b/ast/ast.go
@@ -0,0 +1,48 @@
+package ast
+
+import (
+	"github.com/mewsen/interpreter/token"
+)
+
+type Node interface {
+	TokenLiteral() string
+}
+
+type Statement interface {
+	Node
+	statementNode()
+}
+
+type Expression interface {
+	Node
+	expressionNode()
+}
+
+type Program struct {
+	Statements []Statement
+}
+
+func (p *Program) TokenLiteral() string {
+	if len(p.Statements) > 0 {
+		return p.Statements[0].TokenLiteral()
+	} else {
+		return ""
+	}
+}
+
+type LetStatement struct {
+	Token token.Token
+	Name  *Identifier
+	Value Expression
+}
+
+func (ls *LetStatement) statementNode()       {}
+func (ls *LetStatement) TokenLiteral() string { return ls.Token.Literal }
+
+type Identifier struct {
+	Token token.Token
+	Value string
+}
+
+func (i *Identifier) expressionNode()      {}
+func (i *Identifier) TokenLiteral() string { return i.Token.Literal }
diff --git a/lexer/repl/repl.go b/lexer/repl/repl.go
new file mode 100644
index 0000000..ef3d418
--- /dev/null
+++ b/lexer/repl/repl.go
@@ -0,0 +1,31 @@
+package repl
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+
+	"github.com/mewsen/interpreter/lexer"
+	"github.com/mewsen/interpreter/token"
+)
+
+const PROMPT = ">> "
+
+func Start(in io.Reader, out io.Writer) {
+	scanner := bufio.NewScanner(in)
+
+	for {
+		fmt.Fprintf(out, PROMPT)
+		scanned := scanner.Scan()
+		if !scanned {
+			return
+		}
+
+		line := scanner.Text()
+		l := lexer.New(line)
+
+		for tok := l.NextToken(); tok.Type != token.EOF; tok = l.NextToken() {
+			fmt.Fprintf(out, "%+v\n", tok)
+		}
+	}
+}
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..b759ba9
--- /dev/null
+++ b/main.go
@@ -0,0 +1,11 @@
+package main
+
+import (
+	"os"
+
+	"github.com/mewsen/interpreter/lexer/repl"
+)
+
+func main() {
+	repl.Start(os.Stdin, os.Stdout)
+}
diff --git a/parser/parser.go b/parser/parser.go
new file mode 100644
index 0000000..5840f0a
--- /dev/null
+++ b/parser/parser.go
@@ -0,0 +1,32 @@
+package parser
+
+import (
+	"github.com/mewsen/interpreter/ast"
+	"github.com/mewsen/interpreter/lexer"
+	"github.com/mewsen/interpreter/token"
+)
+
+type Parser struct {
+	l *lexer.Lexer
+
+	curToken  token.Token
+	peekToken token.Token
+}
+
+func (p *Parser) NextToken() {
+	p.curToken = p.peekToken
+	p.peekToken = p.l.NextToken()
+}
+
+func New(l *lexer.Lexer) *Parser {
+	p := &Parser{l: l}
+
+	p.NextToken()
+	p.NextToken()
+
+	return p
+}
+
+func (p *Parser) ParseProgram() *ast.Program {
+	return nil
+}
-- 
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