Merge remote-tracking branch 'origin/topic/jsiwek/while'

Added documentation to statement reference.

* origin/topic/jsiwek/while:
  Add 'while' statement to Bro language.

BIT-1315 #merged

CHANGES

@@ -1,4 +1,8 @@
 
+2.3-426 | 2015-02-20 12:45:51 -0800
+
+  * Add 'while' statement to Bro language. Really. (Jon Siwek)
+
 2.3-424 | 2015-02-20 12:39:10 -0800
 
   * Add the ability to remove surrounding braces from the JSON

NEWS

@@ -31,6 +31,14 @@ New Functionality
 - Bro's file analysis now supports reassembly of files that are not
   transferred/seen sequentially.
 
+- Bro's scripting language now has a ``while`` statement::
+
+        while ( i < 5 )
+            print ++i;
+
+  ``next`` and ``break`` can be used inside the loop's body just like
+  with ``for`` loops.
+
 Changed Functionality
 ---------------------
 

VERSION

@@ -1 +1 @@
-2.3-424
+2.3-426

doc/script-reference/statements.rst

@@ -45,8 +45,11 @@ Statements
 |                            | file                   |
 +----------------------------+------------------------+
 | :bro:keyword:`for`,        | Loop over each         |
-| :bro:keyword:`next`,       | element in a container |
-| :bro:keyword:`break`       | object                 |
+| :bro:keyword:`while`,      | element in a container |
+| :bro:keyword:`next`,       | object (``for``), or   |
+| :bro:keyword:`break`       | as long as a condition |
+|                            | evaluates to true      |
+|                            | (``while``).           |
 +----------------------------+------------------------+
 | :bro:keyword:`if`          | Evaluate boolean       |
 |                            | expression and if true,|
@@ -563,6 +566,36 @@ Here are the statements that the Bro scripting language supports.
     See the :bro:keyword:`return` statement for an explanation of how to
     create an asynchronous function in a Bro script.
 
+.. bro:keyword:: while
+
+    A "while" loop iterates over a body statement as long a given
+    condition remains true.
+
+    A :bro:keyword:`break` statement can be used at any time to immediately
+    terminate the "while" loop, and a :bro:keyword:`next` statement can be
+    used to skip to the next loop iteration.
+
+    Example::
+
+        local i = 0;
+
+        while ( i < 5 )
+            print ++i;
+
+        while ( some_cond() )
+            {
+            local finish_up = F;
+
+            if ( skip_ahead() )
+                next;
+
+            [...]
+
+            if ( finish_up )
+                break;
+
+            [...]
+            }
 
 .. _compound statement:
 

src/SerialTypes.h

@@ -181,6 +181,7 @@ SERIAL_STMT(INIT_STMT, 17)
 SERIAL_STMT(NULL_STMT, 18)
 SERIAL_STMT(WHEN_STMT, 19)
 SERIAL_STMT(FALLTHROUGH_STMT, 20)
+SERIAL_STMT(WHILE_STMT, 21)
 
 #define SERIAL_TYPE(name, val) SERIAL_CONST(name, val, BRO_TYPE)
 SERIAL_TYPE(BRO_TYPE, 1)

src/Stmt.cc

@@ -23,7 +23,7 @@ const char* stmt_name(BroStmtTag t)
 		"print", "event", "expr", "if", "when", "switch",
 		"for", "next", "break", "return", "add", "delete",
 		"list", "bodylist",
-		"<init>", "fallthrough",
+		"<init>", "fallthrough", "while",
 		"null",
 	};
 
@@ -1127,6 +1127,126 @@ bool EventStmt::DoUnserialize(UnserialInfo* info)
 	return event_expr != 0;
 	}
 
+WhileStmt::WhileStmt(Expr* arg_loop_condition, Stmt* arg_body)
+	: loop_condition(arg_loop_condition), body(arg_body)
+	{
+	if ( ! loop_condition->IsError() &&
+	     ! IsBool(loop_condition->Type()->Tag()) )
+		loop_condition->Error("while conditional must be boolean");
+	}
+
+WhileStmt::~WhileStmt()
+	{
+	Unref(loop_condition);
+	Unref(body);
+	}
+
+int WhileStmt::IsPure() const
+	{
+	return loop_condition->IsPure() && body->IsPure();
+	}
+
+void WhileStmt::Describe(ODesc* d) const
+	{
+	Stmt::Describe(d);
+
+	if ( d->IsReadable() )
+		d->Add("(");
+
+	loop_condition->Describe(d);
+
+	if ( d->IsReadable() )
+		d->Add(")");
+
+	d->SP();
+	d->PushIndent();
+	body->AccessStats(d);
+	body->Describe(d);
+	d->PopIndent();
+	}
+
+TraversalCode WhileStmt::Traverse(TraversalCallback* cb) const
+	{
+	TraversalCode tc = cb->PreStmt(this);
+	HANDLE_TC_STMT_PRE(tc);
+
+	tc = loop_condition->Traverse(cb);
+	HANDLE_TC_STMT_PRE(tc);
+
+	tc = body->Traverse(cb);
+	HANDLE_TC_STMT_PRE(tc);
+
+	tc = cb->PostStmt(this);
+	HANDLE_TC_STMT_POST(tc);
+	}
+
+Val* WhileStmt::Exec(Frame* f, stmt_flow_type& flow) const
+	{
+	RegisterAccess();
+	flow = FLOW_NEXT;
+	Val* rval = 0;
+
+	for ( ; ; )
+		{
+		Val* cond = loop_condition->Eval(f);
+
+		if ( ! cond )
+			break;
+
+		bool cont = cond->AsBool();
+		Unref(cond);
+
+		if ( ! cont )
+			break;
+
+		flow = FLOW_NEXT;
+		rval = body->Exec(f, flow);
+
+		if ( flow == FLOW_BREAK || flow == FLOW_RETURN )
+			break;
+		}
+
+	if ( flow == FLOW_LOOP || flow == FLOW_BREAK )
+		flow = FLOW_NEXT;
+
+	return rval;
+	}
+
+Stmt* WhileStmt::Simplify()
+	{
+	loop_condition = simplify_expr(loop_condition, SIMPLIFY_GENERAL);
+
+	if ( loop_condition->IsConst() && loop_condition->IsZero() )
+		return new NullStmt();
+
+	body = simplify_stmt(body);
+	return this;
+	}
+
+IMPLEMENT_SERIAL(WhileStmt, SER_WHILE_STMT);
+
+bool WhileStmt::DoSerialize(SerialInfo* info) const
+	{
+	DO_SERIALIZE(SER_WHILE_STMT, Stmt);
+
+	if ( ! loop_condition->Serialize(info) )
+		return false;
+
+	return body->Serialize(info);
+	}
+
+bool WhileStmt::DoUnserialize(UnserialInfo* info)
+	{
+	DO_UNSERIALIZE(Stmt);
+	loop_condition = Expr::Unserialize(info);
+
+	if ( ! loop_condition )
+		return false;
+
+	body = Stmt::Unserialize(info);
+	return body != 0;
+	}
+
 ForStmt::ForStmt(id_list* arg_loop_vars, Expr* loop_expr)
 : ExprStmt(STMT_FOR, loop_expr)
 	{

src/Stmt.h

@@ -310,6 +310,33 @@ protected:
 	EventExpr* event_expr;
 };
 
+class WhileStmt : public Stmt {
+public:
+
+	WhileStmt(Expr* loop_condition, Stmt* body);
+	~WhileStmt();
+
+	int IsPure() const;
+
+	void Describe(ODesc* d) const;
+
+	TraversalCode Traverse(TraversalCallback* cb) const;
+
+protected:
+	friend class Stmt;
+
+	WhileStmt()
+		{ loop_condition = 0; body = 0; }
+
+	Val* Exec(Frame* f, stmt_flow_type& flow) const;
+	Stmt* Simplify();
+
+	DECLARE_SERIAL(WhileStmt);
+
+	Expr* loop_condition;
+	Stmt* body;
+};
+
 class ForStmt : public ExprStmt {
 public:
 	ForStmt(id_list* loop_vars, Expr* loop_expr);

src/StmtEnums.h

@@ -17,6 +17,7 @@ typedef enum {
 	STMT_LIST, STMT_EVENT_BODY_LIST,
 	STMT_INIT,
 	STMT_FALLTHROUGH,
+	STMT_WHILE,
 	STMT_NULL
 #define NUM_STMTS (int(STMT_NULL) + 1)
 } BroStmtTag;

src/parse.y

@@ -16,6 +16,7 @@
 %token TOK_REMOVE_FROM TOK_RETURN TOK_SCHEDULE TOK_SET
 %token TOK_STRING TOK_SUBNET TOK_SWITCH TOK_TABLE
 %token TOK_TIME TOK_TIMEOUT TOK_TIMER TOK_TYPE TOK_UNION TOK_VECTOR TOK_WHEN
+%token TOK_WHILE
 
 %token TOK_ATTR_ADD_FUNC TOK_ATTR_ENCRYPT TOK_ATTR_DEFAULT
 %token TOK_ATTR_OPTIONAL TOK_ATTR_REDEF TOK_ATTR_ROTATE_INTERVAL
@@ -1340,6 +1341,11 @@ stmt:
 			$1->AsForStmt()->AddBody($2);
 			}
 
+	|	TOK_WHILE '(' expr ')' stmt
+			{
+			$$ = new WhileStmt($3, $5);
+			}
+
 	|	TOK_NEXT ';' opt_no_test
 			{
 			set_location(@1, @2);

src/scan.l

@@ -221,6 +221,7 @@ export	return TOK_EXPORT;
 fallthrough	return TOK_FALLTHROUGH;
 file	return TOK_FILE;
 for	return TOK_FOR;
+while	return TOK_WHILE;
 function	return TOK_FUNCTION;
 global	return TOK_GLOBAL;
 "?$"	return TOK_HAS_FIELD;

testing/btest/Baseline/language.while/out

@@ -0,0 +1,12 @@
+10
+s
+ss
+sss
+{
+7,
+1,
+9,
+5,
+3
+}
+[number 0, number 1, number 2, number 3, number 4, number 5, number 6, number 7, number 8, number 9, number 10, number 11, number 12]

testing/btest/core/leaks/while.bro

@@ -0,0 +1,80 @@
+# @TEST-GROUP: leaks
+# @TEST-REQUIRES: bro --help 2>&1 | grep -q mem-leaks
+
+# @TEST-EXEC: HEAP_CHECK_DUMP_DIRECTORY=. HEAPCHECK=local btest-bg-run bro bro -m -b -r $TRACES/http/get.trace %INPUT
+# @TEST-EXEC: btest-bg-wait 30
+
+function test_noop()
+	{
+	while ( F )
+		print "noooooooooo";
+	}
+
+function test_it()
+	{
+	local i = 0;
+
+	while ( i < 10 )
+		++i;
+
+	print i;
+	}
+
+function test_break()
+	{
+	local s = "";
+
+	while ( T )
+		{
+		s += "s";
+		print s;
+
+		if ( s == "sss" )
+			break;
+		}
+	}
+
+function test_next()
+	{
+	local s: set[count];
+	local i = 0;
+
+	while ( 9 !in s )
+		{
+		++i;
+
+		if ( i % 2 == 0 )
+			next;
+
+		add s[i];
+		}
+
+	print s;
+	}
+
+function test_return(): vector of string
+	{
+	local i = 0;
+	local rval: vector of string;
+
+	while ( T )
+		{
+		rval[i] = fmt("number %d", i);
+		++i;
+
+		if ( i == 13 )
+			return rval;
+		}
+
+	rval[0] = "noooo";
+	return rval;
+	}
+
+event new_connection(c: connection)
+	{
+	test_noop();
+	test_it();
+	test_break();
+	test_next();
+	print test_return();
+	}

testing/btest/language/while.bro

@@ -0,0 +1,77 @@
+# @TEST-EXEC: bro -b %INPUT >out
+# @TEST-EXEC: btest-diff out
+
+function test_noop()
+	{
+	while ( F )
+		print "noooooooooo";
+	}
+
+function test_it()
+	{
+	local i = 0;
+
+	while ( i < 10 )
+		++i;
+
+	print i;
+	}
+
+function test_break()
+	{
+	local s = "";
+
+	while ( T )
+		{
+		s += "s";
+		print s;
+
+		if ( s == "sss" )
+			break;
+		}
+	}
+
+function test_next()
+	{
+	local s: set[count];
+	local i = 0;
+
+	while ( 9 !in s )
+		{
+		++i;
+
+		if ( i % 2 == 0 )
+			next;
+
+		add s[i];
+		}
+
+	print s;
+	}
+
+function test_return(): vector of string
+	{
+	local i = 0;
+	local rval: vector of string;
+
+	while ( T )
+		{
+		rval[i] = fmt("number %d", i);
+		++i;
+
+		if ( i == 13 )
+			return rval;
+		}
+
+	rval[0] = "noooo";
+	return rval;
+	}
+
+event bro_init()
+	{
+	test_noop();
+	test_it();
+	test_break();
+	test_next();
+	print test_return();
+	}