From a50265860470ab53ee137536d738cdc57ff47e72 Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Wed, 21 Oct 2020 23:42:40 -0700
Subject: Add Scanner for Lox

---
 src/com/craftinginterpreters/lox/Lox.java | 64 +++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 src/com/craftinginterpreters/lox/Lox.java

(limited to 'src/com/craftinginterpreters/lox/Lox.java')

diff --git a/src/com/craftinginterpreters/lox/Lox.java b/src/com/craftinginterpreters/lox/Lox.java
new file mode 100644
index 0000000..51d72c7
--- /dev/null
+++ b/src/com/craftinginterpreters/lox/Lox.java
@@ -0,0 +1,64 @@
+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 {
+    private 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.print("> ");
+            String line = reader.readLine();
+            if (line == null) break;
+            run(line);
+            hadError = false;
+        }
+    }
+
+    private static void run(String source) {
+        Scanner scanner = new Scanner(source);
+        List<Token> tokens = scanner.scanTokens();
+
+        // For now, just print the tokens.
+        for (Token token : tokens) {
+            System.out.println(token);
+        }
+    }
+
+    public 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;
+    }
+}
-- 
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