commit 27211247b7e5b3faf098af5afaf0c5532752e372 Author: Gal Date: Wed Feb 7 23:34:26 2024 +0100 Initial commit diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..80d855c --- /dev/null +++ b/.gitignore @@ -0,0 +1,50 @@ +# Compiled class file +*.class + +# Log files +*.log + +# BlueJ files +*.ctxt + +# Mobile Tools for Java (J2ME) +.mtj.tmp/ + +# Package Files # +*.jar +*.war +*.nar +*.ear +*.zip +*.tar.gz +*.rar + +# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml +hs_err_pid* + +# VSCode # +.vscode/ + +# Gradle # +.gradle/ +build/ + +# Intellij # +.idea/ + +# Eclipse # +.classpath +.project +.settings/ + +# NetBeans # +nbproject/private/ +build/ +nbbuild/ +dist/ +nbdist/ +nbactions.xml +nb-configuration.xml + +# Maven # +target/ diff --git a/README.md b/README.md new file mode 100644 index 0000000..44d67ad --- /dev/null +++ b/README.md @@ -0,0 +1,13 @@ +## Crafting Interpreters + +### Running + +``` +cd src +javac -d ../bin com/craftinginterpreters/lox/*.java + +cd .. +java -cp bin com.craftinginterpreters.lox.Lox + +jlox [script] +``` \ No newline at end of file diff --git a/src/com/craftinginterpreters/lox/Lox.java b/src/com/craftinginterpreters/lox/Lox.java new file mode 100644 index 0000000..ff048e6 --- /dev/null +++ b/src/com/craftinginterpreters/lox/Lox.java @@ -0,0 +1,65 @@ +package com.craftinginterpreters.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 runFile(String path) throws IOException { + byte[] bytes = Files.readAllBytes(Paths.get(path)); + run(new String(bytes, Charset.defaultCharset())); + + // Indicate an error in the exit code + 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.println("> "); + String line = reader.readLine(); + if (line == null) + break; + run(line); + hadError = false; + } + } + + private static void run(String source) { + Scanner scanner = new Scanner(source); + List tokens = scanner.scanTokens(); + + 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; + } +} diff --git a/src/com/craftinginterpreters/lox/Scanner.java b/src/com/craftinginterpreters/lox/Scanner.java new file mode 100644 index 0000000..3faac96 --- /dev/null +++ b/src/com/craftinginterpreters/lox/Scanner.java @@ -0,0 +1,226 @@ +package com.craftinginterpreters.lox; + +import static com.craftinginterpreters.lox.TokenType.*; + +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +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); + + } + + 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); + case '<': + addToken(match('=') ? LESS_EQUAL : LESS); + case '>': + addToken(match('=') ? GREATER_EQUAL : GREATER); + break; + + case '/': + if (match('/')) { + while (peek() != '\n' && !isAtEnd()) + advance(); + } else { + addToken(SLASH); + } + break; + + case ' ': + case '\r': + case '\t': + break; + + case '\n': + line++; + break; + + case '"': + string(); + break; + + default: + if (isDigit(c)) { + number(); + } else if (isAlpha(c)) { + identifier(); + } else { + Lox.error(line, Character.toString(c)); + } + + break; + } + } + + public boolean isDigit(char c) { + return c >= '0' && c <= '9'; + } + + private void number() { + while (isDigit(peek())) + advance(); + + if (peek() == '.' && isDigit(peekNext())) { + advance(); + + while (isDigit(peek())) + advance(); + } + + addToken(NUMBER, Double.parseDouble(source.substring(start, current))); + } + + 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 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 char peekNext() { + if (current + 1 >= source.length()) + return '\0'; + return source.charAt(current + 1); + } + + public void string() { + while (peek() != '"' && !isAtEnd()) { + if (peek() == '\n') + line++; + advance(); + } + + if (isAtEnd()) { + Lox.error(line, "Unterminated string."); + return; + } + + advance(); + + 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; + } + + // Like advance, but does not consume the character + private char peek() { + if (isAtEnd()) + return '\0'; + return source.charAt(current); + } + + private boolean isAtEnd() { + return current >= source.length(); + } + + private char advance() { + return source.charAt(current++); + } + + private void addToken(TokenType type) { + addToken(type, null); + } + + // Grabs the text of the current lexeme and creates a new token for it + private void addToken(TokenType type, Object literal) { + String text = source.substring(start, current); + tokens.add(new Token(type, text, literal, line)); + } +} \ No newline at end of file diff --git a/src/com/craftinginterpreters/lox/Token.java b/src/com/craftinginterpreters/lox/Token.java new file mode 100644 index 0000000..84762a4 --- /dev/null +++ b/src/com/craftinginterpreters/lox/Token.java @@ -0,0 +1,19 @@ +package com.craftinginterpreters.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/craftinginterpreters/lox/TokenType.java b/src/com/craftinginterpreters/lox/TokenType.java new file mode 100644 index 0000000..89e513a --- /dev/null +++ b/src/com/craftinginterpreters/lox/TokenType.java @@ -0,0 +1,17 @@ +package com.craftinginterpreters.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 +} \ No newline at end of file