antlr-3.4/tool/src/test/java/org/antlr/test/TestTokenRewriteStream.java

/*
 * [The "BSD license"]
 *  Copyright (c) 2010 Terence Parr
 *  All rights reserved.
 *
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 *  modification, are permitted provided that the following conditions
 *  are met:
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 *      notice, this list of conditions and the following disclaimer.
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 *      notice, this list of conditions and the following disclaimer in the
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 *  3. The name of the author may not be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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package org.antlr.test;

import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CharStream;
import org.antlr.runtime.TokenRewriteStream;
import org.antlr.tool.Grammar;
import org.antlr.tool.Interpreter;
import org.junit.Test;

public class TestTokenRewriteStream extends BaseTest {

    /** Public default constructor used by TestRig */
    public TestTokenRewriteStream() {
    }

	@Test public void testInsertBeforeIndex0() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.insertBefore(0, "0");
		String result = tokens.toString();
		String expecting = "0abc";
		assertEquals(expecting, result);
	}

	@Test public void testInsertAfterLastIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.insertAfter(2, "x");
		String result = tokens.toString();
		String expecting = "abcx";
		assertEquals(expecting, result);
	}

	@Test public void test2InsertBeforeAfterMiddleIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(1, "x");
		tokens.insertAfter(1, "x");
		String result = tokens.toString();
		String expecting = "axbxc";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceIndex0() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(0, "x");
		String result = tokens.toString();
		String expecting = "xbc";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceLastIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, "x");
		String result = tokens.toString();
		String expecting = "abx";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceMiddleIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(1, "x");
		String result = tokens.toString();
		String expecting = "axc";
		assertEquals(expecting, result);
	}

    @Test public void testToStringStartStop() throws Exception {
        Grammar g = new Grammar(
            "lexer grammar t;\n"+
            "ID : 'a'..'z'+;\n" +
            "INT : '0'..'9'+;\n" +
            "SEMI : ';';\n" +
            "MUL : '*';\n" +
            "ASSIGN : '=';\n" +
            "WS : ' '+;\n");
        // Tokens: 0123456789
        // Input:  x = 3 * 0;
        CharStream input = new ANTLRStringStream("x = 3 * 0;");
        Interpreter lexEngine = new Interpreter(g, input);
        TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
        tokens.fill();
        tokens.replace(4, 8, "0"); // replace 3 * 0 with 0

        String result = tokens.toOriginalString();
        String expecting = "x = 3 * 0;";
        assertEquals(expecting, result);

        result = tokens.toString();
        expecting = "x = 0;";
        assertEquals(expecting, result);

        result = tokens.toString(0,9);
        expecting = "x = 0;";
        assertEquals(expecting, result);

        result = tokens.toString(4,8);
        expecting = "0";
        assertEquals(expecting, result);
    }

    @Test public void testToStringStartStop2() throws Exception {
        Grammar g = new Grammar(
            "lexer grammar t;\n"+
            "ID : 'a'..'z'+;\n" +
            "INT : '0'..'9'+;\n" +
            "SEMI : ';';\n" +
            "ASSIGN : '=';\n" +
            "PLUS : '+';\n" +
            "MULT : '*';\n" +
            "WS : ' '+;\n");
        // Tokens: 012345678901234567
        // Input:  x = 3 * 0 + 2 * 0;
        CharStream input = new ANTLRStringStream("x = 3 * 0 + 2 * 0;");
        Interpreter lexEngine = new Interpreter(g, input);
        TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
        tokens.fill();

        String result = tokens.toOriginalString();
        String expecting = "x = 3 * 0 + 2 * 0;";
        assertEquals(expecting, result);

        tokens.replace(4, 8, "0"); // replace 3 * 0 with 0
        result = tokens.toString();
        expecting = "x = 0 + 2 * 0;";
        assertEquals(expecting, result);

        result = tokens.toString(0,17);
        expecting = "x = 0 + 2 * 0;";
        assertEquals(expecting, result);

        result = tokens.toString(4,8);
        expecting = "0";
        assertEquals(expecting, result);

        result = tokens.toString(0,8);
        expecting = "x = 0";
        assertEquals(expecting, result);

        result = tokens.toString(12,16);
        expecting = "2 * 0";
        assertEquals(expecting, result);

        tokens.insertAfter(17, "// comment");
        result = tokens.toString(12,18);
        expecting = "2 * 0;// comment";
        assertEquals(expecting, result);

        result = tokens.toString(0,8); // try again after insert at end
        expecting = "x = 0";
        assertEquals(expecting, result);
    }


    @Test public void test2ReplaceMiddleIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(1, "x");
		tokens.replace(1, "y");
		String result = tokens.toString();
		String expecting = "ayc";
		assertEquals(expecting, result);
	}

    @Test public void test2ReplaceMiddleIndex1InsertBefore() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
        tokens.insertBefore(0, "_");
        tokens.replace(1, "x");
		tokens.replace(1, "y");
		String result = tokens.toString();
		String expecting = "_ayc";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceThenDeleteMiddleIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(1, "x");
		tokens.delete(1);
		String result = tokens.toString();
		String expecting = "ac";
		assertEquals(expecting, result);
	}

	@Test public void testInsertInPriorReplace() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(0, 2, "x");
		tokens.insertBefore(1, "0");
		Exception exc = null;
		try {
			tokens.toString();
		}
		catch (IllegalArgumentException iae) {
			exc = iae;
		}
		String expecting = "insert op <InsertBeforeOp@[@1,1:1='b',<5>,1:1]:\"0\"> within boundaries of previous <ReplaceOp@[@0,0:0='a',<4>,1:0]..[@2,2:2='c',<6>,1:2]:\"x\">";
		assertNotNull(exc);
		assertEquals(expecting, exc.getMessage());
	}

	@Test public void testInsertThenReplaceSameIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(0, "0");
		tokens.replace(0, "x"); // supercedes insert at 0
		String result = tokens.toString();
		String expecting = "0xbc";
		assertEquals(expecting, result);
	}

	@Test public void test2InsertMiddleIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(1, "x");
		tokens.insertBefore(1, "y");
		String result = tokens.toString();
		String expecting = "ayxbc";
		assertEquals(expecting, result);
	}

	@Test public void test2InsertThenReplaceIndex0() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(0, "x");
		tokens.insertBefore(0, "y");
		tokens.replace(0, "z");
		String result = tokens.toString();
		String expecting = "yxzbc";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceThenInsertBeforeLastIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, "x");
		tokens.insertBefore(2, "y");
		String result = tokens.toString();
		String expecting = "abyx";
		assertEquals(expecting, result);
	}

	@Test public void testInsertThenReplaceLastIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(2, "y");
		tokens.replace(2, "x");
		String result = tokens.toString();
		String expecting = "abyx";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceThenInsertAfterLastIndex() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, "x");
		tokens.insertAfter(2, "y");
		String result = tokens.toString();
		String expecting = "abxy";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceRangeThenInsertAtLeftEdge() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcccba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 4, "x");
		tokens.insertBefore(2, "y");
		String result = tokens.toString();
		String expecting = "abyxba";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceRangeThenInsertAtRightEdge() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcccba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 4, "x");
		tokens.insertBefore(4, "y"); // no effect; within range of a replace
		Exception exc = null;
		try {
			tokens.toString();
		}
		catch (IllegalArgumentException iae) {
			exc = iae;
		}
		String expecting = "insert op <InsertBeforeOp@[@4,4:4='c',<6>,1:4]:\"y\"> within boundaries of previous <ReplaceOp@[@2,2:2='c',<6>,1:2]..[@4,4:4='c',<6>,1:4]:\"x\">";
		assertNotNull(exc);
		assertEquals(expecting, exc.getMessage());
	}

	@Test public void testReplaceRangeThenInsertAfterRightEdge() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcccba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 4, "x");
		tokens.insertAfter(4, "y");
		String result = tokens.toString();
		String expecting = "abxyba";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceAll() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcccba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(0, 6, "x");
		String result = tokens.toString();
		String expecting = "x";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceSubsetThenFetch() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcccba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 4, "xyz");
		String result = tokens.toString(0,6);
		String expecting = "abxyzba";
		assertEquals(expecting, result);
	}

	@Test public void testReplaceThenReplaceSuperset() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcccba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 4, "xyz");
		tokens.replace(3, 5, "foo"); // overlaps, error
		Exception exc = null;
		try {
			tokens.toString();
		}
		catch (IllegalArgumentException iae) {
			exc = iae;
		}
		String expecting = "replace op boundaries of <ReplaceOp@[@3,3:3='c',<6>,1:3]..[@5,5:5='b',<5>,1:5]:\"foo\"> overlap with previous <ReplaceOp@[@2,2:2='c',<6>,1:2]..[@4,4:4='c',<6>,1:4]:\"xyz\">";
		assertNotNull(exc);
		assertEquals(expecting, exc.getMessage());
	}

	@Test public void testReplaceThenReplaceLowerIndexedSuperset() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcccba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 4, "xyz");
		tokens.replace(1, 3, "foo"); // overlap, error
		Exception exc = null;
		try {
			tokens.toString();
		}
		catch (IllegalArgumentException iae) {
			exc = iae;
		}
		String expecting = "replace op boundaries of <ReplaceOp@[@1,1:1='b',<5>,1:1]..[@3,3:3='c',<6>,1:3]:\"foo\"> overlap with previous <ReplaceOp@[@2,2:2='c',<6>,1:2]..[@4,4:4='c',<6>,1:4]:\"xyz\">";
		assertNotNull(exc);
		assertEquals(expecting, exc.getMessage());
	}

	@Test public void testReplaceSingleMiddleThenOverlappingSuperset() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcba");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 2, "xyz");
		tokens.replace(0, 3, "foo");
		String result = tokens.toString();
		String expecting = "fooa";
		assertEquals(expecting, result);
	}

	// June 2, 2008 I rewrote core of rewrite engine; just adding lots more tests here

	@Test public void testCombineInserts() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(0, "x");
		tokens.insertBefore(0, "y");
		String result = tokens.toString();
		String expecting = "yxabc";
		assertEquals(expecting, result);
	}

	@Test public void testCombine3Inserts() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(1, "x");
		tokens.insertBefore(0, "y");
		tokens.insertBefore(1, "z");
		String result = tokens.toString();
		String expecting = "yazxbc";
		assertEquals(expecting, result);
	}

	@Test public void testCombineInsertOnLeftWithReplace() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(0, 2, "foo");
		tokens.insertBefore(0, "z"); // combine with left edge of rewrite
		String result = tokens.toString();
		String expecting = "zfoo";
		assertEquals(expecting, result);
	}

	@Test public void testCombineInsertOnLeftWithDelete() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.delete(0, 2);
		tokens.insertBefore(0, "z"); // combine with left edge of rewrite
		String result = tokens.toString();
		String expecting = "z"; // make sure combo is not znull
		assertEquals(expecting, result);
	}

	@Test public void testDisjointInserts() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(1, "x");
		tokens.insertBefore(2, "y");
		tokens.insertBefore(0, "z");
		String result = tokens.toString();
		String expecting = "zaxbyc";
		assertEquals(expecting, result);
	}

	@Test public void testOverlappingReplace() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(1, 2, "foo");
		tokens.replace(0, 3, "bar"); // wipes prior nested replace
		String result = tokens.toString();
		String expecting = "bar";
		assertEquals(expecting, result);
	}

	@Test public void testOverlappingReplace2() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(0, 3, "bar");
		tokens.replace(1, 2, "foo"); // cannot split earlier replace
		Exception exc = null;
		try {
			tokens.toString();
		}
		catch (IllegalArgumentException iae) {
			exc = iae;
		}
		String expecting = "replace op boundaries of <ReplaceOp@[@1,1:1='b',<5>,1:1]..[@2,2:2='c',<6>,1:2]:\"foo\"> overlap with previous <ReplaceOp@[@0,0:0='a',<4>,1:0]..[@3,3:3='c',<6>,1:3]:\"bar\">";
		assertNotNull(exc);
		assertEquals(expecting, exc.getMessage());
	}

	@Test public void testOverlappingReplace3() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(1, 2, "foo");
		tokens.replace(0, 2, "bar"); // wipes prior nested replace
		String result = tokens.toString();
		String expecting = "barc";
		assertEquals(expecting, result);
	}

	@Test public void testOverlappingReplace4() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(1, 2, "foo");
		tokens.replace(1, 3, "bar"); // wipes prior nested replace
		String result = tokens.toString();
		String expecting = "abar";
		assertEquals(expecting, result);
	}

	@Test public void testDropIdenticalReplace() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(1, 2, "foo");
		tokens.replace(1, 2, "foo"); // drop previous, identical
		String result = tokens.toString();
		String expecting = "afooc";
		assertEquals(expecting, result);
	}

	@Test public void testDropPrevCoveredInsert() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(1, "foo");
		tokens.replace(1, 2, "foo"); // kill prev insert
		String result = tokens.toString();
		String expecting = "afoofoo";
		assertEquals(expecting, result);
	}

	@Test public void testLeaveAloneDisjointInsert() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(1, "x");
		tokens.replace(2, 3, "foo");
		String result = tokens.toString();
		String expecting = "axbfoo";
		assertEquals(expecting, result);
	}

	@Test public void testLeaveAloneDisjointInsert2() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abcc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.replace(2, 3, "foo");
		tokens.insertBefore(1, "x");
		String result = tokens.toString();
		String expecting = "axbfoo";
		assertEquals(expecting, result);
	}

	@Test public void testInsertBeforeTokenThenDeleteThatToken() throws Exception {
		Grammar g = new Grammar(
			"lexer grammar t;\n"+
			"A : 'a';\n" +
			"B : 'b';\n" +
			"C : 'c';\n");
		CharStream input = new ANTLRStringStream("abc");
		Interpreter lexEngine = new Interpreter(g, input);
		TokenRewriteStream tokens = new TokenRewriteStream(lexEngine);
		tokens.fill();
		tokens.insertBefore(2, "y");
		tokens.delete(2);
		String result = tokens.toString();
		String expecting = "aby";
		assertEquals(expecting, result);
	}

}