From 1d38acda73dcc4f2693f12197ecf8a4fd92c51dd Mon Sep 17 00:00:00 2001 From: adnanioricce Date: Wed, 21 Aug 2024 12:45:05 -0300 Subject: [PATCH] [Init&Scanning] - Chapter 4 follow up - Chapter 4 follow up from the "crafting interpreters" book - Changing the package name ``com.craftinginterpreters.lox`` to ``com.lox`` --- .gitignore | 24 +++++ README.md | 2 + run.sh | 9 ++ shell.nix | 13 +++ src/com/lox/Lox.java | 62 ++++++++++++ src/com/lox/Scanner.java | 197 +++++++++++++++++++++++++++++++++++++ src/com/lox/Token.java | 19 ++++ src/com/lox/TokenType.java | 23 +++++ 8 files changed, 349 insertions(+) create mode 100644 .gitignore create mode 100644 README.md create mode 100755 run.sh create mode 100644 shell.nix create mode 100644 src/com/lox/Lox.java create mode 100644 src/com/lox/Scanner.java create mode 100644 src/com/lox/Token.java create mode 100644 src/com/lox/TokenType.java diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..af213ca --- /dev/null +++ b/.gitignore @@ -0,0 +1,24 @@ +# Compiled class file +*.class + +# Log file +*.log + +# BlueJ files +*.ctxt + +# Mobile Tools for Java (J2ME) +.mtj.tmp/ + +# Package Files # +*.jar +*.war +*.nar +*.ear +*.zip +*.tar.gz +*.rar +out/ +# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml +hs_err_pid* +replay_pid* diff --git a/README.md b/README.md new file mode 100644 index 0000000..81890ef --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +# jlox: the lox java implementation follow up from CraftingInterpreters +The java implementation for the lox language from the reading of Crafting Interpreters diff --git a/run.sh b/run.sh new file mode 100755 index 0000000..7e8ed4b --- /dev/null +++ b/run.sh @@ -0,0 +1,9 @@ +#!/bin/bash + +# Compile +javac -d out src/com/lox/*.java + +# Run + +java -cp out com.lox.Lox + diff --git a/shell.nix b/shell.nix new file mode 100644 index 0000000..3e7a630 --- /dev/null +++ b/shell.nix @@ -0,0 +1,13 @@ +{ pkgs ? import {} }: + +pkgs.mkShell { + buildInputs = [ + pkgs.openjdk + ]; + + shellHook = '' + chmod +x run.sh + echo "Java environment is ready. You can now compile and run your Java programs." + ''; +} + diff --git a/src/com/lox/Lox.java b/src/com/lox/Lox.java new file mode 100644 index 0000000..c53c0d9 --- /dev/null +++ b/src/com/lox/Lox.java @@ -0,0 +1,62 @@ +package com.lox; + +import java.io.BufferedReader; +import java.io.IOException; +import java.io.InputStreamReader; +import java.nio.charset.Charset; +import java.nio.file.Files; +import java.nio.file.Paths; +import java.util.List; + +public class Lox { + static boolean hadError = false; + public static void main(String[] args) throws IOException { + if (args.length > 1) { + System.out.println("Usage: jlox [script]"); + System.exit(64); + } else if (args.length == 1) { + runFile(args[0]); + } else { + runPrompt(); + } + } + + private static void run(String source) { + Scanner scanner = new Scanner(source); + List tokens = scanner.scanTokens(); + + // For now, just print the tokens. + for (Token token : tokens) { + System.out.println(token); + } + } + static void error(int line, String message) { + report(line, "", message); + } + + private static void report(int line, String where, + String message) { + System.err.println( + "[line " + line + "] Error" + where + ": " + message); + hadError = true; + } + + + private static void runFile(String path) throws IOException { + byte[] bytes = Files.readAllBytes(Paths.get(path)); + run(new String(bytes, Charset.defaultCharset())); + if(hadError) System.exit(65); + } + private static void runPrompt() throws IOException { + InputStreamReader input = new InputStreamReader(System.in); + BufferedReader reader = new BufferedReader(input); + + for (;;) { + System.out.print("> "); + String line = reader.readLine(); + if (line == null) break; + run(line); + hadError = false; + } + } +} diff --git a/src/com/lox/Scanner.java b/src/com/lox/Scanner.java new file mode 100644 index 0000000..1a3621f --- /dev/null +++ b/src/com/lox/Scanner.java @@ -0,0 +1,197 @@ +package com.lox; + +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +import static com.lox.TokenType.*; + +class Scanner { + private final String source; + private final List tokens = new ArrayList<>(); + private int start = 0; + private int current = 0; + private int line = 1; + private static final Map keywords; + + static { + keywords = new HashMap<>(); + keywords.put("and", AND); + keywords.put("class", CLASS); + keywords.put("else", ELSE); + keywords.put("false", FALSE); + keywords.put("for", FOR); + keywords.put("fun", FUN); + keywords.put("if", IF); + keywords.put("nil", NIL); + keywords.put("or", OR); + keywords.put("print", PRINT); + keywords.put("return", RETURN); + keywords.put("super", SUPER); + keywords.put("this", THIS); + keywords.put("true", TRUE); + keywords.put("var", VAR); + keywords.put("while", WHILE); + } + Scanner(String source) { + this.source = source; + } + List scanTokens() { + while (!isAtEnd()) { + // We are at the beginning of the next lexeme. + start = current; + scanToken(); + } + + tokens.add(new Token(EOF, "", null, line)); + return tokens; + } + private void scanToken() { + char c = advance(); + switch (c) { + case '(': addToken(LEFT_PAREN); break; + case ')': addToken(RIGHT_PAREN); break; + case '{': addToken(LEFT_BRACE); break; + case '}': addToken(RIGHT_BRACE); break; + case ',': addToken(COMMA); break; + case '.': addToken(DOT); break; + case '-': addToken(MINUS); break; + case '+': addToken(PLUS); break; + case ';': addToken(SEMICOLON); break; + case '*': addToken(STAR); break; + case '!': + addToken(match('=') ? BANG_EQUAL : BANG); + break; + case '=': + addToken(match('=') ? EQUAL_EQUAL : EQUAL); + break; + case '<': + addToken(match('=') ? LESS_EQUAL : LESS); + break; + case '>': + addToken(match('=') ? GREATER_EQUAL : GREATER); + break; + case '/': + if (match('/')) { + // A comment goes until the end of the line. + while (peek() != '\n' && !isAtEnd()) advance(); + } else { + addToken(SLASH); + } + break; + case ' ': + case '\r': + case '\t': + // Ignore whitespace. + break; + + case '\n': + line++; + break; + case '"': string(); break; + case 'o': + if (match('r')) { + addToken(OR); + } + break; + default: + if (isDigit(c)) { + number(); + } + else if(isAlpha(c)){ + identifier(); + } + else { + Lox.error(line, "Unexpected character."); + } + break; + } + } + private void identifier() { + while (isAlphaNumeric(peek())) advance(); + String text = source.substring(start, current); + TokenType type = keywords.get(text); + if (type == null) type = IDENTIFIER; + addToken(type); + } + private void number() { + while (isDigit(peek())) advance(); + + // Look for a fractional part. + if (peek() == '.' && isDigit(peekNext())) { + // Consume the "." + advance(); + + while (isDigit(peek())) advance(); + } + + addToken(NUMBER, + Double.parseDouble(source.substring(start, current))); + } + private void string() { + while (peek() != '"' && !isAtEnd()) { + if (peek() == '\n') line++; + advance(); + } + + if (isAtEnd()) { + Lox.error(line, "Unterminated string."); + return; + } + + // The closing ". + advance(); + + // Trim the surrounding quotes. + String value = source.substring(start + 1, current - 1); + addToken(STRING, value); + } + + private boolean match(char expected) { + if (isAtEnd()) return false; + if (source.charAt(current) != expected) return false; + + current++; + return true; + } + + private char peek() { + if (isAtEnd()) return '\0'; + return source.charAt(current); + } + + private char peekNext() { + if (current + 1 >= source.length()) return '\0'; + return source.charAt(current + 1); + } + + private boolean isAlpha(char c) { + return (c >= 'a' && c <= 'z') || + (c >= 'A' && c <= 'Z') || + c == '_'; + } + + private boolean isAlphaNumeric(char c) { + return isAlpha(c) || isDigit(c); + } + + private boolean isDigit(char c) { + return c >= '0' && c <= '9'; + } + private boolean isAtEnd() { + return current >= source.length(); + } + private char advance() { + return source.charAt(current++); + } + + private void addToken(TokenType type) { + addToken(type, null); + } + + private void addToken(TokenType type, Object literal) { + String text = source.substring(start, current); + tokens.add(new Token(type, text, literal, line)); + } +} diff --git a/src/com/lox/Token.java b/src/com/lox/Token.java new file mode 100644 index 0000000..c974fd0 --- /dev/null +++ b/src/com/lox/Token.java @@ -0,0 +1,19 @@ +package com.lox; + +class Token { + final TokenType type; + final String lexeme; + final Object literal; + final int line; + + Token(TokenType type, String lexeme, Object literal, int line) { + this.type = type; + this.lexeme = lexeme; + this.literal = literal; + this.line = line; + } + + public String toString() { + return type + " " + lexeme + " " + literal; + } +} diff --git a/src/com/lox/TokenType.java b/src/com/lox/TokenType.java new file mode 100644 index 0000000..507e39a --- /dev/null +++ b/src/com/lox/TokenType.java @@ -0,0 +1,23 @@ +package com.lox; + +enum TokenType { + // Single-character tokens. + LEFT_PAREN, RIGHT_PAREN, LEFT_BRACE, RIGHT_BRACE, + COMMA, DOT, MINUS, PLUS, SEMICOLON, SLASH, STAR, + + // One or two character tokens. + BANG, BANG_EQUAL, + EQUAL, EQUAL_EQUAL, + GREATER, GREATER_EQUAL, + LESS, LESS_EQUAL, + + // Literals. + IDENTIFIER, STRING, NUMBER, + + // Keywords. + AND, CLASS, ELSE, FALSE, FUN, FOR, IF, NIL, OR, + PRINT, RETURN, SUPER, THIS, TRUE, VAR, WHILE, + + EOF +} +