[SCM] master: Improve expression error messages.

[cagney@sourceware.org]

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- Log -----------------------------------------------------------------
commit 6e677cc7a7c3844c9d40f64034ff41a4c24f5600
Author: Andrew Cagney <cagney@redhat.com>
Date:   Tue Dec 11 22:43:20 2007 -0500

    Improve expression error messages.
    
    frysk-core/frysk/expr/ChangeLog
    2007-12-11  Andrew Cagney  <cagney@redhat.com>
    
    	* TestArithmetics.java (checkErrorExpr(String,String)): New.
    	(testEndOfFileError()): New.
    	(testExpressionError()): New.
    	(checkVariableExpr(String expr, long value)): New.
    	(testMember()): New.
    	(expr(String)): Delete.
    	(checkScratchExpr(String,long)): Replace checkExpr(long,String).
    	* SyntaxException.java: New.
    	* TestVariables.java: Delete; merge into TestArithmetics.java.
    	* ExpressionFactory.java (parse(ExprSymTab,String)): Do not append
    	ETX character; handle antlr exceptions.
    	(complete(ExprSymTab,String,int,List)): Ditto.
    	* CExpr.g: Terminate the expression with EOF, not ETX.

-----------------------------------------------------------------------

Summary of changes:
 frysk-core/frysk/expr/CExpr.g                      |    5 +-
 frysk-core/frysk/expr/ChangeLog                    |   16 ++++
 frysk-core/frysk/expr/ExpressionFactory.java       |   28 ++++----
 .../{DetailedAST.java => SyntaxException.java}     |   40 +++++-----
 frysk-core/frysk/expr/TestArithmetics.java         |   40 ++++++++--
 frysk-core/frysk/expr/TestVariables.java           |   75 --------------------
 6 files changed, 82 insertions(+), 122 deletions(-)
 copy frysk-core/frysk/expr/{DetailedAST.java => SyntaxException.java} (73%)
 delete mode 100644 frysk-core/frysk/expr/TestVariables.java

First 500 lines of diff:
diff --git a/frysk-core/frysk/expr/CExpr.g b/frysk-core/frysk/expr/CExpr.g
index 037ba18..a154ff1 100644
--- a/frysk-core/frysk/expr/CExpr.g
+++ b/frysk-core/frysk/expr/CExpr.g
@@ -119,14 +119,11 @@ imaginaryTokenDefinitions
     ;
 
 /** 
-  * The start rule simply expects an expression list following by
-  * the end of text symbol (ETX \3).
-  *
   * The TabException propagates all the way up, to the start rule,
   * which then propagates it up to the calling program.
   */
 start
-    :   expressionList ETX
+    :   expressionList EOF
     ;
 
 /** 
diff --git a/frysk-core/frysk/expr/ChangeLog b/frysk-core/frysk/expr/ChangeLog
index ac90071..01f7557 100644
--- a/frysk-core/frysk/expr/ChangeLog
+++ b/frysk-core/frysk/expr/ChangeLog
@@ -1,3 +1,19 @@
+2007-12-11  Andrew Cagney  <cagney@redhat.com>
+
+	* TestArithmetics.java (checkErrorExpr(String,String)): New.
+	(testEndOfFileError()): New.
+	(testExpressionError()): New.
+	(checkVariableExpr(String expr, long value)): New.
+	(testMember()): New.
+	(expr(String)): Delete.
+	(checkScratchExpr(String,long)): Replace checkExpr(long,String).
+	* SyntaxException.java: New.
+	* TestVariables.java: Delete; merge into TestArithmetics.java.
+	* ExpressionFactory.java (parse(ExprSymTab,String)): Do not append
+	ETX character; handle antlr exceptions.
+	(complete(ExprSymTab,String,int,List)): Ditto.
+	* CExpr.g: Terminate the expression with EOF, not ETX.
+
 2007-11-28  Sami Wagiaalla  <swagiaal@redhat.com>
 
 	CompositeType.java: Renamed addStaticBitFieldMember and 
diff --git a/frysk-core/frysk/expr/ExpressionFactory.java b/frysk-core/frysk/expr/ExpressionFactory.java
index 879f399..d2d325d 100644
--- a/frysk-core/frysk/expr/ExpressionFactory.java
+++ b/frysk-core/frysk/expr/ExpressionFactory.java
@@ -54,18 +54,17 @@ public class ExpressionFactory {
     public static int complete(ExprSymTab symTab, String incomplete,
 			       int offset, List candidates) {
 	try {
-	    String input = (incomplete.substring(0, offset)
-			    + '\t'
-			    + incomplete.substring(offset)
-			    +(char) 3);
+	    String input = incomplete.substring(0, offset) + '\t';
 	    CExprLexer lexer = new CExprLexer(new StringReader(input));
 	    CExprParser parser = new CExprParser(lexer);
 	    parser.setASTNodeClass(DetailedAST.class.getName());
 	    parser.start();
 	} catch (antlr.RecognitionException e) {
-	    throw new RuntimeException(e);
+	    // Unexpected input, don't complete.
+	    return -1;
 	} catch (antlr.TokenStreamException e) {
-	    throw new RuntimeException(e);
+	    // Unexpected token, don't complete.
+	    return -1;
 	} catch (CompletionException e) {
 	    int newOffset = e.complete(symTab, candidates);
 	    Collections.sort(candidates);
@@ -78,21 +77,20 @@ public class ExpressionFactory {
 	return -1; // nothing completed.
     }
 
-
     /**
-     * Parse the string, returning an expression.
+     * Parse the string, returning an expression; or throwing
+     * SyntaxException.
      */
     public static Expression parse(ExprSymTab symTab, String expression) {
 	try {
-	    String input = expression + (char)3;
-	    CExprParser parser
-		= new CExprParser(new CExprLexer(new StringReader(input)));
+	    StringReader input = new StringReader(expression);
+	    CExprParser parser = new CExprParser(new CExprLexer(input));
 	    parser.start();
 	    return new Expression(symTab, parser.getAST());
-	} catch (antlr.RecognitionException r) {
-	    throw new RuntimeException(r);
-	} catch (antlr.TokenStreamException t) {
-	    throw new RuntimeException(t);
+	} catch (antlr.RecognitionException e) {
+	    throw new SyntaxException(expression, e);
+	} catch (antlr.TokenStreamException e) {
+	    throw new SyntaxException(expression, e);
 	}
     }
 }
diff --git a/frysk-core/frysk/expr/DetailedAST.java b/frysk-core/frysk/expr/SyntaxException.java
similarity index 73%
copy from frysk-core/frysk/expr/DetailedAST.java
copy to frysk-core/frysk/expr/SyntaxException.java
index bfe069a..1161c40 100644
--- a/frysk-core/frysk/expr/DetailedAST.java
+++ b/frysk-core/frysk/expr/SyntaxException.java
@@ -1,6 +1,6 @@
 // This file is part of the program FRYSK.
 //
-// Copyright 2007, Red Hat Inc.
+// Copyright 2007 Red Hat Inc.
 //
 // FRYSK is free software; you can redistribute it and/or modify it
 // under the terms of the GNU General Public License as published by
@@ -39,31 +39,31 @@
 
 package frysk.expr;
 
-import antlr.CommonAST;
-import antlr.Token;
+import antlr.RecognitionException;
+import antlr.TokenStreamException;
 
-/** 
- * An AST that also retains the location of its token.
- *
- * For what ever reason the default ast doesn't remember the location
- * (line/col) of a token.
+/**
+ * Some sort of syntax error.
  */
 
-public class DetailedAST extends CommonAST {
+public class SyntaxException extends RuntimeException {
     static final long serialVersionUID = 1;
-    public DetailedAST() {
+
+    private static String message(String input, RecognitionException e) {
+	int cursor = e.getColumn() - 1; // antlr counts from 1.
+	if (input.length() == cursor)
+	    return "incomplete expression";
+	else
+	    return "invalid expression at: " + input.substring(cursor);
     }
-    private int column;
-    private int line;
-    public void initialize(Token t) {
-	super.initialize(t);
-	this.column = t.getColumn();
-	this.line = t.getLine();
+    SyntaxException(String input, RecognitionException e) {
+	super(message(input, e), e);
     }
-    public int getColumn() {
-	return column;
+
+    private static String message(String input, TokenStreamException e) {
+	return "unexpected input: " + e.getMessage();
     }
-    public int getLine() {
-	return line;
+    SyntaxException(String input, TokenStreamException e) {
+	super(message(input, e), e);
     }
 }
diff --git a/frysk-core/frysk/expr/TestArithmetics.java b/frysk-core/frysk/expr/TestArithmetics.java
index d70eac3..7968a76 100644
--- a/frysk-core/frysk/expr/TestArithmetics.java
+++ b/frysk-core/frysk/expr/TestArithmetics.java
@@ -40,8 +40,6 @@
 package frysk.expr;
 
 import frysk.junit.TestCase;
-import frysk.value.Value;
-import frysk.expr.ScratchSymTab;
 
 /**
  * Scratch is for the case where there isn't any symbols, basic ops
@@ -49,16 +47,42 @@ import frysk.expr.ScratchSymTab;
  */
 
 public class TestArithmetics extends TestCase {
-    private Value eval(String input) {
+    private void checkScratchExpr(String expr, long value) {
 	ExprSymTab symTab = new ScratchSymTab();
-	return ExpressionFactory.parse(symTab, input).getValue();
+	Expression e = ExpressionFactory.parse(symTab, expr);
+	assertEquals(expr, value, e.getValue().asLong());
+    }
+    public void testAdd() {
+	checkScratchExpr("1 + 2", 3);
     }
 
-    private void checkExpr(long value, String expr) {
-	assertEquals(expr, value, eval(expr).asLong());
+    private void checkVariableExpr(String expr, long value) {
+	ExprSymTab symTab = new TestbedSymTab();
+	Expression e = ExpressionFactory.parse(symTab, expr);
+	assertEquals(expr, value, e.getValue().asLong());
+    }
+    public void testMember() {
+	checkVariableExpr("a.alpha", 0x01020304);
     }
 
-    public void testAdd() {
-	checkExpr(3, "1 + 2");
+    private void checkErrorExpr(String input, String error) {
+	Throwable t = null;
+	try {
+	    ExprSymTab symTab = new ScratchSymTab();
+	    ExpressionFactory.parse(symTab, input);
+	} catch (SyntaxException e) {
+	    t = e;
+	}
+	assertNotNull("error", t);
+	assertEquals("error", error, t.getMessage());
+    }
+    public void testEndOfFileError() {
+	checkErrorExpr("&", "incomplete expression");
+    }
+    public void testExpressionError() {
+	checkErrorExpr("1 . 2", "invalid expression at: 2");
+    }
+    public void testTokenError() {
+	checkErrorExpr("1...2", "unexpected input: expecting '.', found '2'");
     }
 }
diff --git a/frysk-core/frysk/expr/TestVariables.java b/frysk-core/frysk/expr/TestVariables.java
deleted file mode 100644
index 00015a6..0000000
--- a/frysk-core/frysk/expr/TestVariables.java
+++ /dev/null
@@ -1,75 +0,0 @@
-// This file is part of the program FRYSK.
-//
-// Copyright 2007 Red Hat Inc.
-//
-// FRYSK is free software; you can redistribute it and/or modify it
-// under the terms of the GNU General Public License as published by
-// the Free Software Foundation; version 2 of the License.
-//
-// FRYSK is distributed in the hope that it will be useful, but
-// WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-// General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with FRYSK; if not, write to the Free Software Foundation,
-// Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
-// 
-// In addition, as a special exception, Red Hat, Inc. gives You the
-// additional right to link the code of FRYSK with code not covered
-// under the GNU General Public License ("Non-GPL Code") and to
-// distribute linked combinations including the two, subject to the
-// limitations in this paragraph. Non-GPL Code permitted under this
-// exception must only link to the code of FRYSK through those well
-// defined interfaces identified in the file named EXCEPTION found in
-// the source code files (the "Approved Interfaces"). The files of
-// Non-GPL Code may instantiate templates or use macros or inline
-// functions from the Approved Interfaces without causing the
-// resulting work to be covered by the GNU General Public
-// License. Only Red Hat, Inc. may make changes or additions to the
-// list of Approved Interfaces. You must obey the GNU General Public
-// License in all respects for all of the FRYSK code and other code
-// used in conjunction with FRYSK except the Non-GPL Code covered by
-// this exception. If you modify this file, you may extend this
-// exception to your version of the file, but you are not obligated to
-// do so. If you do not wish to provide this exception without
-// modification, you must delete this exception statement from your
-// version and license this file solely under the GPL without
-// exception.
-
-package frysk.expr;
-
-import frysk.junit.TestCase;
-import frysk.value.Value;
-import java.io.StringReader;
-
-/**
- * Anything more complex than 1+1.
- */
-
-public class TestVariables extends TestCase {
-
-    private Value eval(String input) {
-	try {
-	    input += (char) 3;
-	    CExprLexer lexer = new CExprLexer(new StringReader(input));
-	    CExprParser parser = new CExprParser(lexer);
-	    parser.start();
-	    ExprSymTab symTab = new TestbedSymTab();
-	    CExprEvaluator exprEvaluator = new CExprEvaluator(symTab);
-	    return exprEvaluator.expr(parser.getAST());
-	} catch (antlr.RecognitionException e) {
-	    throw new RuntimeException(e);
-	} catch (antlr.TokenStreamException e) {
-	    throw new RuntimeException(e);
-	}
-    }
-
-    private void checkExpr(long value, String expr) {
-	assertEquals(expr, value, eval(expr).asLong());
-    }
-
-    public void testMember() {
-	checkExpr(0x01020304, "a.alpha");
-    }
-}


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