Вывод информации о позиции в исходнике, где произошла ошибка

src/com/annimon/ownlang/parser/Lexer.java

@@ -59,12 +59,14 @@ public final class Lexer {
     private final List<Token> tokens;
     
     private int pos;
+    private int row, col;
 
     public Lexer(String input) {
         this.input = input;
         length = input.length();
         
         tokens = new ArrayList<>();
+        row = col = 1;
     }
     
     public List<Token> tokenize() {
@@ -92,7 +94,7 @@ public final class Lexer {
         char current = peek(0);
         while (true) {
             if (current == '.') {
-                if (buffer.indexOf(".") != -1) throw new RuntimeException("Invalid float number");
+                if (buffer.indexOf(".") != -1) throw error("Invalid float number");
             } else if (!Character.isDigit(current)) {
                 break;
             }
@@ -178,6 +180,7 @@ public final class Lexer {
         final StringBuilder buffer = new StringBuilder();
         char current = peek(0);
         while (true) {
+            if (current == '\0') throw error("Reached end of file while parsing text string.");
             if (current == '\\') {
                 current = next();
                 switch (current) {
@@ -207,7 +210,7 @@ public final class Lexer {
     private void tokenizeMultilineComment() {
         char current = peek(0);
         while (true) {
-            if (current == '\0') throw new RuntimeException("Missing close tag");
+            if (current == '\0') throw error("Reached end of file while parsing multiline comment");
             if (current == '*' && peek(1) == '/') break;
             current = next();
         }
@@ -217,7 +220,12 @@ public final class Lexer {
     
     private char next() {
         pos++;
-        return peek(0);
+        final char result = peek(0);
+        if (result == '\n') {
+            row++;
+            col = 1;
+        } else col++;
+        return result;
     }
     
     private char peek(int relativePosition) {
@@ -231,6 +239,10 @@ public final class Lexer {
     }
     
     private void addToken(TokenType type, String text) {
-        tokens.add(new Token(type, text));
+        tokens.add(new Token(type, text, row, col));
+    }
+    
+    private LexerException error(String text) {
+        return new LexerException(row, col, text);
     }
 }

src/com/annimon/ownlang/parser/LexerException.java

@@ -0,0 +1,16 @@
+package com.annimon.ownlang.parser;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class LexerException extends RuntimeException {
+
+    public LexerException(String message) {
+        super(message);
+    }
+    
+    public LexerException(int row, int col, String message) {
+        super("["+row+":"+col+"] " + message);
+    }
+}

src/com/annimon/ownlang/parser/ParseException.java

@@ -0,0 +1,16 @@
+package com.annimon.ownlang.parser;
+
+/**
+ *
+ * @author aNNiMON
+ */
+public final class ParseException extends RuntimeException {
+    
+    public ParseException() {
+        super();
+    }
+    
+    public ParseException(String string) {
+        super(string);
+    }
+}

src/com/annimon/ownlang/parser/Parser.java

@@ -10,7 +10,7 @@ import java.util.List;
  */
 public final class Parser {
     
-    private static final Token EOF = new Token(TokenType.EOF, "");
+    private static final Token EOF = new Token(TokenType.EOF, "", -1, -1);
 
     private final List<Token> tokens;
     private final int size;
@@ -82,7 +82,6 @@ public final class Parser {
     }
     
     private Statement assignmentStatement() {
-        // WORD EQ
         if (lookMatch(0, TokenType.WORD) && lookMatch(1, TokenType.EQ)) {
             final String variable = consume(TokenType.WORD).getText();
             consume(TokenType.EQ);
@@ -93,7 +92,7 @@ public final class Parser {
             consume(TokenType.EQ);
             return new ArrayAssignmentStatement(array, expression());
         }
-        throw new RuntimeException("Unknown statement");
+        throw new ParseException("Unknown statement: " + get(0));
     }
     
     private Statement ifElse() {
@@ -128,7 +127,7 @@ public final class Parser {
         final Expression termination = expression();
         consume(TokenType.COMMA);
         final Statement increment = assignmentStatement();
-        match(TokenType.RPAREN);
+        match(TokenType.RPAREN); // необязательные скобки
         final Statement statement = statementOrBlock();
         return new ForStatement(initialization, termination, increment, statement);
     }
@@ -409,12 +408,12 @@ public final class Parser {
             match(TokenType.RPAREN);
             return result;
         }
-        throw new RuntimeException("Unknown expression");
+        throw new ParseException("Unknown expression: " + current);
     }
     
     private Token consume(TokenType type) {
         final Token current = get(0);
-        if (type != current.getType()) throw new RuntimeException("Token " + current + " doesn't match " + type);
+        if (type != current.getType()) throw new ParseException("Token " + current + " doesn't match " + type);
         pos++;
         return current;
     }

src/com/annimon/ownlang/parser/Token.java

@@ -6,35 +6,39 @@ package com.annimon.ownlang.parser;
  */
 public final class Token {
 
-    private TokenType type;
-    private String text;
+    private final TokenType type;
+    private final String text;
+    private final int row, col;
     
-    public Token() {
-    }
-
-    public Token(TokenType type, String text) {
+    public Token(TokenType type, String text, int row, int col) {
         this.type = type;
         this.text = text;
+        this.row = row;
+        this.col = col;
     }
 
     public TokenType getType() {
         return type;
     }
 
-    public void setType(TokenType type) {
-        this.type = type;
-    }
-
     public String getText() {
         return text;
     }
 
-    public void setText(String text) {
-        this.text = text;
+    public int getRow() {
+        return row;
+    }
+
+    public int getCol() {
+        return col;
+    }
+    
+    public String position() {
+        return "[" + row + " " + col + "]";
     }
 
     @Override
     public String toString() {
-        return type + " " + text;
+        return type.name() + " " + position() + " " + text;
     }
 }