Dafny: don't require parentheses in syntax of "choose" statements

6 files changed, 86 insertions, 104 deletions

diff --git a/Dafny/Dafny.atg b/Dafny/Dafny.atg
index 2b330706..7d7a496c 100644
--- a/Dafny/Dafny.atg
+++ b/Dafny/Dafny.atg
@@ -810,7 +810,7 @@ AssignRhs<.out List<Expression> ee, out Type ty, out CallStmt initCall, Expressi
                                                                   receiverForInitCall, x.val, args); .)

     ]

   | "choose"                           (. x = t; .)

-    "(" Expression<out e> ")"          (. e = new UnaryExpr(x, UnaryExpr.Opcode.SetChoose, e);

+    Expression<out e>                  (. e = new UnaryExpr(x, UnaryExpr.Opcode.SetChoose, e);

                                           ee = new List<Expression>() { e };

                                        .)

   | Expression<out e>                  (. ee = new List<Expression>() { e }; .)

diff --git a/Dafny/Parser.cs b/Dafny/Parser.cs
index 5c1e473b..988b73e2 100644
--- a/Dafny/Parser.cs
+++ b/Dafny/Parser.cs
@@ -25,7 +25,7 @@ public class Parser {
 	const bool T = true;

 	const bool x = false;

 	const int minErrDist = 2;

-

+	

 	public Scanner/*!*/ scanner;

 	public Errors/*!*/  errors;

 

@@ -161,10 +161,10 @@ public static int Parse (string/*!*/ s, string/*!*/ filename, List<ModuleDecl/*!
 		if (errDist >= minErrDist) errors.SemErr(t, msg);

 		errDist = 0;

 	}

-

-	public void SemErr(IToken/*!*/ tok, string/*!*/ msg) {

-	  Contract.Requires(tok != null);

-	  Contract.Requires(msg != null);

+	

+    public void SemErr(IToken/*!*/ tok, string/*!*/ msg) {

+      Contract.Requires(tok != null);

+      Contract.Requires(msg != null);

 	  errors.SemErr(tok, msg);

 	}

 

@@ -177,15 +177,15 @@ public static int Parse (string/*!*/ s, string/*!*/ filename, List<ModuleDecl/*!
 			la = t;

 		}

 	}

-

+	

 	void Expect (int n) {

 		if (la.kind==n) Get(); else { SynErr(n); }

 	}

-

+	

 	bool StartOf (int s) {

 		return set[s, la.kind];

 	}

-

+	

 	void ExpectWeak (int n, int follow) {

 		if (la.kind == n) Get();

 		else {

@@ -209,7 +209,7 @@ public static int Parse (string/*!*/ s, string/*!*/ filename, List<ModuleDecl/*!
 		}

 	}

 

-

+	

 	void Dafny() {

 		ClassDecl/*!*/ c; DatatypeDecl/*!*/ dt;

 		Attributes attrs;  IToken/*!*/ id;  List<string/*!*/> theImports;

@@ -1423,9 +1423,7 @@ List<Expression/*!*/>/*!*/ decreases) {
 		} else if (la.kind == 52) {

 			Get();

 			x = t; 

-			Expect(30);

 			Expression(out e);

-			Expect(31);

 			e = new UnaryExpr(x, UnaryExpr.Opcode.SetChoose, e);

 			ee = new List<Expression>() { e };

 			

@@ -2107,13 +2105,13 @@ List<Expression/*!*/>/*!*/ decreases) {
 

 	public void Parse() {

 		la = new Token();

-		la.val = "";

+		la.val = "";		

 		Get();

 		Dafny();

 

-		Expect(0);

+    Expect(0);

 	}

-

+	

 	static readonly bool[,]/*!*/ set = {

 		{T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

 		{x,x,x,x, x,T,x,x, x,T,T,T, T,T,T,x, T,x,T,x, x,x,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

@@ -2142,20 +2140,18 @@ List<Expression/*!*/>/*!*/ decreases) {
 public class Errors {

 	public int count = 0;                                    // number of errors detected

 	public System.IO.TextWriter/*!*/ errorStream = Console.Out;   // error messages go to this stream

-	public string errMsgFormat = "{0}({1},{2}): error: {3}"; // 0=filename, 1=line, 2=column, 3=text

-	public string warningMsgFormat = "{0}({1},{2}): warning: {3}"; // 0=filename, 1=line, 2=column, 3=text

-

+  public string errMsgFormat = "{0}({1},{2}): error: {3}"; // 0=filename, 1=line, 2=column, 3=text

+  public string warningMsgFormat = "{0}({1},{2}): warning: {3}"; // 0=filename, 1=line, 2=column, 3=text

+  

 	public void SynErr(string filename, int line, int col, int n) {

-		SynErr(filename, line, col, GetSyntaxErrorString(n));

-	}

-

-	public virtual void SynErr(string filename, int line, int col, string/*!*/ msg) {

-		Contract.Requires(msg != null);

+    SynErr(filename, line, col, GetSyntaxErrorString(n));

+  }

+	public virtual void SynErr(string filename, int line, int col, string msg) {

+	  Contract.Requires(msg != null);

 		errorStream.WriteLine(errMsgFormat, filename, line, col, msg);

 		count++;

-	}

-

-	string GetSyntaxErrorString(int n) {

+  }

+  string GetSyntaxErrorString(int n) {

 		string s;

 		switch (n) {

 			case 0: s = "EOF expected"; break;

@@ -2310,7 +2306,7 @@ public class Errors {
 

 			default: s = "error " + n; break;

 		}

-		return s;

+    return s;

 	}

 

 	public void SemErr(IToken/*!*/ tok, string/*!*/ msg) {  // semantic errors

@@ -2318,9 +2314,8 @@ public class Errors {
 		Contract.Requires(msg != null);

 		SemErr(tok.filename, tok.line, tok.col, msg);

 	}

-

 	public virtual void SemErr(string filename, int line, int col, string/*!*/ msg) {

-		Contract.Requires(msg != null);

+	  Contract.Requires(msg != null);

 		errorStream.WriteLine(errMsgFormat, filename, line, col, msg);

 		count++;

 	}

diff --git a/Dafny/Printer.cs b/Dafny/Printer.cs
index 6af086a5..ab82add8 100644
--- a/Dafny/Printer.cs
+++ b/Dafny/Printer.cs
@@ -839,28 +839,19 @@ namespace Microsoft.Dafny {
           int opBindingStrength;

           switch (e.Op) {

             case UnaryExpr.Opcode.SetChoose:

-              op = "choose";  opBindingStrength = -1;  break;

+              op = "choose ";  opBindingStrength = 0;  break;

             case UnaryExpr.Opcode.Not:

               op = "!";  opBindingStrength = 0x60;  break;

             default:

               Contract.Assert(false); throw new cce.UnreachableException();  // unexpected unary opcode

           }

-          if (opBindingStrength == -1) {

-            // print as a function

-            wr.Write(op);

-            wr.Write("(");

-            PrintExpression(e.E);

-            wr.Write(")");

-          } else {

-            // print as an operator

-            bool parensNeeded = opBindingStrength < contextBindingStrength ||

-              (fragileContext && opBindingStrength == contextBindingStrength);

+          bool parensNeeded = opBindingStrength < contextBindingStrength ||

+            (fragileContext && opBindingStrength == contextBindingStrength);

 

-            if (parensNeeded) { wr.Write("("); }

-            wr.Write(op);

-            PrintExpr(e.E, opBindingStrength, false, -1);

-            if (parensNeeded) { wr.Write(")"); }

-          }

+          if (parensNeeded) { wr.Write("("); }

+          wr.Write(op);

+          PrintExpr(e.E, opBindingStrength, false, -1);

+          if (parensNeeded) { wr.Write(")"); }

         }

       

       } else if (expr is BinaryExpr) {

diff --git a/Dafny/Scanner.cs b/Dafny/Scanner.cs
index 126c762b..e3c84a73 100644
--- a/Dafny/Scanner.cs
+++ b/Dafny/Scanner.cs
@@ -19,7 +19,7 @@ public class Buffer {
 	//    a) whole stream in buffer

 	//    b) part of stream in buffer

 	// 2) non seekable stream (network, console)

-

+  

 	public const int EOF = 65535 + 1; // char.MaxValue + 1;

 	const int MIN_BUFFER_LENGTH = 1024; // 1KB

 	const int MAX_BUFFER_LENGTH = MIN_BUFFER_LENGTH * 64; // 64KB

@@ -31,17 +31,15 @@ public class Buffer {
 	Stream/*!*/ stream;      // input stream (seekable)

 	bool isUserStream;  // was the stream opened by the user?

 

-	[ContractInvariantMethod]

-	void ObjectInvariant(){

-		Contract.Invariant(buf != null);

-		Contract.Invariant(stream != null);

-	}

-

-//  [NotDelayed]

-	public Buffer (Stream/*!*/ s, bool isUserStream) : base() {

+[ContractInvariantMethod]

+void ObjectInvariant(){

+  Contract.Invariant(buf != null);

+  Contract.Invariant(stream != null);}

+    [NotDelayed]

+	public Buffer (Stream/*!*/ s, bool isUserStream) :base() {

 	  Contract.Requires(s != null);

 		stream = s; this.isUserStream = isUserStream;

-

+		

 		int fl, bl;

 		if (s.CanSeek) {

 			fl = (int) s.Length;

@@ -53,12 +51,12 @@ public class Buffer {
 

 		buf = new byte[(bl>0) ? bl : MIN_BUFFER_LENGTH];

 		fileLen = fl;  bufLen = bl;

-

+		

 		if (fileLen > 0) Pos = 0; // setup buffer to position 0 (start)

 		else bufPos = 0; // index 0 is already after the file, thus Pos = 0 is invalid

 		if (bufLen == fileLen && s.CanSeek) Close();

 	}

-

+	

 	protected Buffer(Buffer/*!*/ b) { // called in UTF8Buffer constructor

 	  Contract.Requires(b != null);

 		buf = b.buf;

@@ -75,14 +73,14 @@ public class Buffer {
 	}

 

 	~Buffer() { Close(); }

-

+	

 	protected void Close() {

 		if (!isUserStream && stream != null) {

 			stream.Close();

 			//stream = null;

 		}

 	}

-

+	

 	public virtual int Read () {

 		if (bufPos < bufLen) {

 			return buf[bufPos++];

@@ -102,7 +100,7 @@ public class Buffer {
 		Pos = curPos;

 		return ch;

 	}

-

+	

 	public string/*!*/ GetString (int beg, int end) {

 	  Contract.Ensures(Contract.Result<string>() != null);

 		int len = 0;

@@ -141,7 +139,7 @@ public class Buffer {
 			}

 		}

 	}

-

+	

 	// Read the next chunk of bytes from the stream, increases the buffer

 	// if needed and updates the fields fileLen and bufLen.

 	// Returns the number of bytes read.

@@ -215,20 +213,19 @@ public class Scanner {
 	const int noSym = 105;

 

 

-	[ContractInvariantMethod]

-	void objectInvariant(){

-		Contract.Invariant(buffer!=null);

-		Contract.Invariant(t != null);

-		Contract.Invariant(start != null);

-		Contract.Invariant(tokens != null);

-		Contract.Invariant(pt != null);

-		Contract.Invariant(tval != null);

-		Contract.Invariant(Filename != null);

-		Contract.Invariant(errorHandler != null);

-	}

-

+[ContractInvariantMethod]

+void objectInvariant(){

+  Contract.Invariant(buffer!=null);

+  Contract.Invariant(t != null);

+  Contract.Invariant(start != null);

+  Contract.Invariant(tokens != null);

+  Contract.Invariant(pt != null);

+  Contract.Invariant(tval != null);

+  Contract.Invariant(Filename != null);

+  Contract.Invariant(errorHandler != null);

+}

 	public Buffer/*!*/ buffer; // scanner buffer

-

+	

 	Token/*!*/ t;          // current token

 	int ch;           // current input character

 	int pos;          // byte position of current character

@@ -239,13 +236,13 @@ public class Scanner {
 

 	Token/*!*/ tokens;     // list of tokens already peeked (first token is a dummy)

 	Token/*!*/ pt;         // current peek token

-

+	

 	char[]/*!*/ tval = new char[128]; // text of current token

 	int tlen;         // length of current token

-

+	

 	private string/*!*/ Filename;

 	private Errors/*!*/ errorHandler;

-

+	

 	static Scanner() {

 		start = new Hashtable(128);

 		for (int i = 39; i <= 39; ++i) start[i] = 1;

@@ -294,9 +291,9 @@ public class Scanner {
 		start[Buffer.EOF] = -1;

 

 	}

-

-//	[NotDelayed]

-	public Scanner (string/*!*/ fileName, Errors/*!*/ errorHandler) : base() {

+	

+	[NotDelayed]

+	public Scanner (string/*!*/ fileName, Errors/*!*/ errorHandler) :base(){

 	  Contract.Requires(fileName != null);

 	  Contract.Requires(errorHandler != null);

 		this.errorHandler = errorHandler;

@@ -306,14 +303,15 @@ public class Scanner {
 			Stream stream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);

 			buffer = new Buffer(stream, false);

 			Filename = fileName;

+			

 			Init();

 		} catch (IOException) {

 			throw new FatalError("Cannot open file " + fileName);

 		}

 	}

-

-//	[NotDelayed]

-	public Scanner (Stream/*!*/ s, Errors/*!*/ errorHandler, string/*!*/ fileName) : base() {

+	

+	[NotDelayed]

+	public Scanner (Stream/*!*/ s, Errors/*!*/ errorHandler, string/*!*/ fileName) :base(){

 	  Contract.Requires(s != null);

 	  Contract.Requires(errorHandler != null);

 	  Contract.Requires(fileName != null);

@@ -322,9 +320,10 @@ public class Scanner {
 		buffer = new Buffer(s, true);

 		this.errorHandler = errorHandler;

 		this.Filename = fileName;

+		

 		Init();

 	}

-

+	

 	void Init() {

 		pos = -1; line = 1; col = 0;

 		oldEols = 0;

@@ -345,11 +344,11 @@ public class Scanner {
 	Contract.Ensures(Contract.Result<string>() != null);

 	  int p = buffer.Pos;

 	  int ch = buffer.Read();

-	  // replace isolated '\r' by '\n' in order to make

+      // replace isolated '\r' by '\n' in order to make

 	  // eol handling uniform across Windows, Unix and Mac

 	  if (ch == '\r' && buffer.Peek() != '\n') ch = EOL;

 	  while (ch != EOL && ch != Buffer.EOF){

-		ch = buffer.Read();

+	    ch = buffer.Read();

 		// replace isolated '\r' by '\n' in order to make

 		// eol handling uniform across Windows, Unix and Mac

 		if (ch == '\r' && buffer.Peek() != '\n') ch = EOL;

@@ -360,7 +359,7 @@ public class Scanner {
 	}

 

 	void NextCh() {

-		if (oldEols > 0) { ch = EOL; oldEols--; }

+		if (oldEols > 0) { ch = EOL; oldEols--; } 

 		else {

 //			pos = buffer.Pos;

 //			ch = buffer.Read(); col++;

@@ -368,9 +367,9 @@ public class Scanner {
 //			// eol handling uniform across Windows, Unix and Mac

 //			if (ch == '\r' && buffer.Peek() != '\n') ch = EOL;

 //			if (ch == EOL) { line++; col = 0; }

-

+			

 			while (true) {

-				pos = buffer.Pos;

+			    pos = buffer.Pos;

 				ch = buffer.Read(); col++;

 				// replace isolated '\r' by '\n' in order to make

 				// eol handling uniform across Windows, Unix and Mac

@@ -420,7 +419,7 @@ public class Scanner {
 				return;

 			  }

 

-

+			

 		}

 

 	}

@@ -558,13 +557,10 @@ public class Scanner {
 		t.pos = pos; t.col = col; t.line = line;

 		t.filename = this.Filename;

 		int state;

-		if (start.ContainsKey(ch)) {

-			Contract.Assert(start[ch] != null);

-			state = (int) start[ch];

-		}

+		if (start.ContainsKey(ch)) { state = (int) cce.NonNull( start[ch]); }

 		else { state = 0; }

 		tlen = 0; AddCh();

-

+		

 		switch (state) {

 			case -1: { t.kind = eofSym; break; } // NextCh already done

 			case 0: {

@@ -771,14 +767,14 @@ public class Scanner {
 		t.val = new String(tval, 0, tlen);

 		return t;

 	}

-

+	

 	private void SetScannerBehindT() {

 		buffer.Pos = t.pos;

 		NextCh();

 		line = t.line; col = t.col;

 		for (int i = 0; i < tlen; i++) NextCh();

 	}

-

+	

 	// get the next token (possibly a token already seen during peeking)

 	public Token/*!*/ Scan () {

 	 Contract.Ensures(Contract.Result<Token>() != null);

@@ -799,7 +795,7 @@ public class Scanner {
 			}

 			pt = pt.next;

 		} while (pt.kind > maxT); // skip pragmas

-

+	

 		return pt;

 	}

 

diff --git a/Test/dafny0/AdvancedLHS.dfy b/Test/dafny0/AdvancedLHS.dfy
index b73af758..4f80eade 100644
--- a/Test/dafny0/AdvancedLHS.dfy
+++ b/Test/dafny0/AdvancedLHS.dfy
@@ -8,7 +8,7 @@ class C {
     x := new C;

     x := new C.Init();

     havoc x;

-    x := choose(S);

+    x := choose S;

 

     // test evaluation order

     var c := x;

diff --git a/Test/dafny1/Celebrity.dfy b/Test/dafny1/Celebrity.dfy
index 25e6cc5c..74512e01 100644
--- a/Test/dafny1/Celebrity.dfy
+++ b/Test/dafny1/Celebrity.dfy
@@ -22,20 +22,20 @@ method FindCelebrity1<Person>(people: set<Person>, ghost c: Person) returns (r:
   ensures r == c;

 {

   var Q := people;

-  var x := choose(Q);

+  var x := choose Q;

   while (Q != {x})

     //invariant Q <= people;  // inv1 in Rodin's Celebrity_1, but it's not needed here

     invariant IsCelebrity(c, Q);  // inv2

     invariant x in Q;

     decreases Q;

   {

-    var y := choose(Q - {x});

+    var y := choose Q - {x};

     if (Knows(x, y)) {

       Q := Q - {x};  // remove_1

     } else {

       Q := Q - {y};  assert x in Q;  // remove_2

     }

-    x := choose(Q);

+    x := choose Q;

   }

   r := x;

 }

@@ -44,7 +44,7 @@ method FindCelebrity2<Person>(people: set<Person>, ghost c: Person) returns (r:
   requires IsCelebrity(c, people);

   ensures r == c;

 {

-  var b := choose(people);

+  var b := choose people;

   var R := people - {b};

   while (R != {})

     invariant R <= people;  // inv1

@@ -54,7 +54,7 @@ method FindCelebrity2<Person>(people: set<Person>, ghost c: Person) returns (r:
 

     decreases R;

   {

-    var x := choose(R);

+    var x := choose R;

     if (Knows(x, b)) {

       R := R - {x};

     } else {