WIP

src/main/java/com/issy/Walker.java

@@ -0,0 +1,23 @@
+package com.issy;
+
+import com.issy.compiler.FileMatcher;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.stream.Stream;
+
+public class Walker {
+
+  public List<String> walk(String startPath, FileMatcher fileMatcher) {
+    try (Stream<Path> pathStream = Files.walk(Path.of(startPath))) {
+      return pathStream.map(Path::toString).filter(fileMatcher::matches).toList();
+    } catch (IOException e) {
+      throw new RuntimeException("Error reading file: " + e.getMessage());
+    } catch (SecurityException e) {
+      throw new RuntimeException("Not permitted to read file: " + e.getMessage());
+    }
+  }
+
+}

src/main/java/com/issy/compiler/Lexer.java

@@ -6,6 +6,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Predicate;
+import java.util.stream.Stream;
 
 import static com.issy.compiler.Token.*;
 
@@ -22,36 +23,37 @@ public Lexer(String input) {
   public List<TokenContext> parse() {
     final List<TokenContext> tokens = new ArrayList<>();
     while (cursor.getValue() < input.length()) {
-      String currentChar = charAt(cursor.getValue());
+      final Position position = positionAt(cursor.getValue());
+      final String currentChar = charAt(cursor.getValue());
       if (currentChar.equals("\"")) {
         String munched = collectUntil(stringLiteralTerminationPredicate(cursor.getValue()));
-        tokens.add(new TokenContext(STRING, parseStringLiteral(munched)));
+        tokens.add(TokenContext.withPosition(STRING, parseStringLiteral(munched), position));
         cursor.increment();
       } else if (currentChar.equals("(")) {
-        tokens.add(new TokenContext(OPEN_PAREN, "("));
+        tokens.add(TokenContext.withPosition(OPEN_PAREN, "(", position));
         cursor.increment();
       } else if (currentChar.equals(")")) {
-        tokens.add(new TokenContext(CLOSE_PAREN, ")"));
+        tokens.add(TokenContext.withPosition(CLOSE_PAREN, ")", position));
         cursor.increment();
       } else if (currentChar.equals("!")) {
-        tokens.add(new TokenContext(NOT, "!"));
+        tokens.add(TokenContext.withPosition(NOT, "!", position));
         cursor.increment();
       } else if (currentChar.equals("&")) {
         if (charAt(cursor.increment()).equals("&")) {
-          tokens.add(new TokenContext(OR, "&&"));
+          tokens.add(TokenContext.withPosition(OR, "&&", position));
         } else {
           throw new RuntimeException("Expected &&");
         }
         cursor.increment();
       } else if (currentChar.equals("|")) {
         if (charAt(cursor.increment()).equals("|")) {
-          tokens.add(new TokenContext(OR, "||"));
+          tokens.add(TokenContext.withPosition(OR, "||", position));
         } else {
           throw new RuntimeException("Expected ||");
         }
         cursor.increment();
       } else if (Character.isLetter(input.charAt(cursor.getValue()))) {
-        tokens.add(new TokenContext(IDENTIFIER, collectUntil(identifierNameTerminationPredicate())));
+        tokens.add(TokenContext.withPosition(IDENTIFIER, collectUntil(identifierNameTerminationPredicate()), position));
       } else if (currentChar.equals(" ") || currentChar.equals("\n") || currentChar.equals("\t") || currentChar.equals("\r")) {
         cursor.increment();
         continue;
@@ -93,6 +95,19 @@ private String charAt(int index) {
     return String.valueOf(input.charAt(index));
   }
 
+  private Position positionAt(int index) {
+    List<String> lines = input.lines().toList();
+    int count = 0;
+    for (int i = 0; i < lines.size(); i++) {
+      String line = lines.get(i);
+      count += line.length();
+      if (count > index) {
+        return new Position(i + 1, index % count);
+      }
+    }
+    throw new IllegalArgumentException("Index exceeds string length");
+  }
+
   private static class Cursor {
 
     private int value;
@@ -126,4 +141,7 @@ public boolean atLimit() {
     }
   }
 
+  public static record Position(Integer line, Integer column) {
+  }
+
 }

src/main/java/com/issy/compiler/TokenContext.java

@@ -1,5 +1,14 @@
 package com.issy.compiler;
 
 // TODO: Include line:col position data for better error messages
-public record TokenContext(Token token, String value) {
+public record TokenContext(Token token, String value, Integer line, Integer column) {
+
+  public static TokenContext withPosition(Token token, String value, Lexer.Position position) {
+    return new TokenContext(token, value, position.line(), position.column());
+  }
+
+  public String getFormattedPosition() {
+    return String.format("%d:%d", line + 1, column);
+  }
+
 }

src/test/java/com/issy/compiler/CompilerTest.java

@@ -12,14 +12,14 @@ class CompilerTest {
   void canCompile() {
     // Given
     final List<TokenContext> tokenContexts = List.of(
-        new TokenContext(Token.IDENTIFIER, Identifier.HAS_FILE_EXTENSION.getName()),
-        new TokenContext(Token.OPEN_PAREN, "("),
-        new TokenContext(Token.STRING, "\".tsx\""),
-        new TokenContext(Token.CLOSE_PAREN, ")"),
-        new TokenContext(Token.AND, "&&"),
-        new TokenContext(Token.IDENTIFIER, Identifier.IS_IN_BASE_DIRECTORY.getName()),
-        new TokenContext(Token.OPEN_PAREN, "("),
-        new TokenContext(Token.CLOSE_PAREN, ")")
+        new TokenContext(Token.IDENTIFIER, Identifier.HAS_FILE_EXTENSION.getName(), 0, 0),
+        new TokenContext(Token.OPEN_PAREN, "(", 0, 0),
+        new TokenContext(Token.STRING, "\".tsx\"", 0, 0),
+        new TokenContext(Token.CLOSE_PAREN, ")", 0, 0),
+        new TokenContext(Token.AND, "&&", 0, 0),
+        new TokenContext(Token.IDENTIFIER, Identifier.IS_IN_BASE_DIRECTORY.getName(), 0, 0),
+        new TokenContext(Token.OPEN_PAREN, "(", 0, 0),
+        new TokenContext(Token.CLOSE_PAREN, ")", 0, 0)
     );
     final Compiler compiler = new Compiler(tokenContexts);