Merge pull request #239 from ThakeeNathees/invalid-assignment-bug

Invalid definition inside expression fixed

scripts/run_tests.py

@@ -33,6 +33,7 @@ TEST_SUITE = {
   "Modules Test" : (
     "modules/dummy.pk",
     "modules/math.pk",
+    "modules/io.File.pk",
   ),
 
   "Random Scripts" : (

src/core/compiler.c

@@ -479,6 +479,18 @@ struct Compiler {
   // "r-value".
   bool l_value;
 
+  // We can do a new assignment inside an expression however we shouldn't
+  // define a new one, since in pocketlang both assignment and definition
+  // are syntactically the same, we use [can_define] "context" to prevent
+  // such assignments.
+  bool can_define;
+
+  // This value will set to true for parsing a temproary expression
+  // (ie. if <expr> ...) and the value of the expression will be popped out of
+  // the stack onece we're done, if it's a defenition, that value should be
+  // duplicated on the stack to prevent it.
+  bool expr_temp;
+
   // This value will be true after parsing a call expression, for every other
   // Expressions it'll be false. This is **ONLY** to be used when compiling a
   // return statement to check if the last parsed expression is a call to
@@ -551,6 +563,8 @@ static void parserInit(Parser* parser, PKVM* vm, Compiler* compiler,
 static void compilerInit(Compiler* compiler, PKVM* vm, const char* source,
                          Module* module, const CompileOptions* options) {
 
+  memset(compiler, 0, sizeof(Compiler));
+
   compiler->next_compiler = NULL;
 
   compiler->module = module;
@@ -561,6 +575,7 @@ static void compilerInit(Compiler* compiler, PKVM* vm, const char* source,
   compiler->loop = NULL;
   compiler->func = NULL;
 
+  compiler->can_define = true;
   compiler->new_local = false;
   compiler->is_last_call = false;
 
@@ -1880,7 +1895,14 @@ static void exprInterpolation(Compiler* compiler) {
 }
 
 static void exprFunction(Compiler* compiler) {
+  bool can_define = compiler->can_define;
+  bool expr_temp = compiler->expr_temp;
+
+  compiler->can_define = true;
+  compiler->expr_temp = false;
   compileFunction(compiler, FUNC_LITERAL);
+  compiler->can_define = can_define;
+  compiler->expr_temp = expr_temp;
 }
 
 static void exprName(Compiler* compiler) {
@@ -1926,10 +1948,18 @@ static void exprName(Compiler* compiler) {
         if (name_type == NAME_LOCAL_VAR) {
           new_local = true;
         }
+
+        if (!compiler->can_define) {
+          semanticError(compiler, tkname,
+            "Variable definition isn't allowed here.");
+        }
       }
 
       // Compile the assigned value.
+      bool can_define = compiler->can_define;
+      compiler->can_define = false;
       compileExpression(compiler);
+      compiler->can_define = can_define;
 
     } else { // name += / -= / *= ... = (expr);
 
@@ -1963,6 +1993,11 @@ static void exprName(Compiler* compiler) {
       // If the compiler has errors, we cannot and don't have to assert.
       ASSERT(compiler->parser.has_errors ||
              (compiler->func->stack_size - 1) == index, OOPS);
+
+      if (compiler->expr_temp) {
+        emitOpcode(compiler, OP_DUP);
+      }
+
     } else {
       // The assigned value or the result of the operator will be at the top of
       // the stack by now. Store it.
@@ -2281,9 +2316,18 @@ static void parsePrecedence(Compiler* compiler, Precedence precedence) {
   // reset once it done.
   bool l_value = compiler->l_value;
 
+  // Inside an expression no new difinition is allowed. We make a "backup"
+  // here to prevent such and reset it once we're done.
+  bool can_define = compiler->can_define;
+  if (prefix != exprName) compiler->can_define = false;
+
   compiler->l_value = precedence <= PREC_LOWEST;
   prefix(compiler);
 
+  // Prefix expression can be either allow or not allow a definition however
+  // an infix expression can never be a definition.
+  compiler->can_define = false;
+
   // The above expression cannot be a call '(', since call is an infix
   // operator. But could be true (ex: x = f()). we set is_last_call to false
   // here and if the next infix operator is call this will be set to true
@@ -2304,6 +2348,7 @@ static void parsePrecedence(Compiler* compiler, Precedence precedence) {
   }
 
   compiler->l_value = l_value;
+  compiler->can_define = can_define;
 }
 
 /*****************************************************************************/
@@ -3041,7 +3086,12 @@ static void compileExpression(Compiler* compiler) {
 static void compileIfStatement(Compiler* compiler, bool elif) {
 
   skipNewLines(compiler);
+
+  bool expr_temp = compiler->expr_temp;
+  compiler->expr_temp = true;
   compileExpression(compiler); //< Condition.
+  compiler->expr_temp = expr_temp;
+
   emitOpcode(compiler, OP_JUMP_IF_NOT);
   int ifpatch = emitShort(compiler, 0xffff); //< Will be patched.
 
@@ -3090,7 +3140,11 @@ static void compileWhileStatement(Compiler* compiler) {
   loop.depth = compiler->scope_depth;
   compiler->loop = &loop;
 
+  bool expr_temp = compiler->expr_temp;
+  compiler->expr_temp = true;
   compileExpression(compiler); //< Condition.
+  compiler->expr_temp = expr_temp;
+
   emitOpcode(compiler, OP_JUMP_IF_NOT);
   int whilepatch = emitShort(compiler, 0xffff); //< Will be patched.
 
@@ -3122,7 +3176,10 @@ static void compileForStatement(Compiler* compiler) {
 
   // Compile and store sequence.
   compilerAddVariable(compiler, "@Sequence", 9, iter_line); // Sequence
+  bool expr_temp = compiler->expr_temp;
+  compiler->expr_temp = true;
   compileExpression(compiler);
+  compiler->expr_temp = expr_temp;
 
   // Add iterator to locals. It's an increasing integer indicating that the
   // current loop is nth starting from 0.
@@ -3233,7 +3290,10 @@ static void compileStatement(Compiler* compiler) {
                     "Cannor 'return' a value from constructor.");
       }
 
+      bool can_define = compiler->can_define;
+      compiler->can_define = false;
       compileExpression(compiler); //< Return value is at stack top.
+      compiler->can_define = can_define;
 
       // If the last expression parsed with compileExpression() is a call
       // is_last_call would be true by now.

src/core/core.c

@@ -737,9 +737,9 @@ DEF(_objTypeName,
 }
 
 DEF(_objRepr,
-  "Object.repr() -> String\n"
+  "Object._repr() -> String\n"
   "Returns the repr string of the object.") {
-  RET(VAR_OBJ(varToString(vm, SELF, true)));
+  RET(VAR_OBJ(toRepr(vm, SELF)));
 }
 
 DEF(_numberTimes,
@@ -1145,7 +1145,7 @@ static void initializePrimitiveClasses(PKVM* vm) {
 
   // TODO: write docs.
   ADD_METHOD(PK_OBJECT, "typename", _objTypeName,    0);
-  ADD_METHOD(PK_OBJECT, "repr",     _objRepr,        0);
+  ADD_METHOD(PK_OBJECT, "_repr",    _objRepr,        0);
 
   ADD_METHOD(PK_NUMBER, "times",  _numberTimes,     1);
   ADD_METHOD(PK_NUMBER, "isint",  _numberIsint,     0);

src/core/debug.c

@@ -374,6 +374,7 @@ void dumpFunctionCode(PKVM* vm, Function* func) {
       case OP_PUSH_TRUE:
       case OP_PUSH_FALSE:
       case OP_SWAP:
+      case OP_DUP:
         NO_ARGS();
         break;
 

src/core/opcodes.h

@@ -33,6 +33,9 @@ OPCODE(PUSH_FALSE, 0, 1)
 // Swap the top 2 stack values.
 OPCODE(SWAP, 0, 0)
 
+// Duplicate the stack top value.
+OPCODE(DUP, 0, 1)
+
 // Push a new list to construct from literal.
 // param: 2 bytes list size (default is 0).
 OPCODE(PUSH_LIST, 2, 1)

src/core/vm.c

@@ -828,6 +828,12 @@ L_vm_main_loop:
       DISPATCH();
     }
 
+    OPCODE(DUP):
+    {
+      PUSH(*(fiber->sp - 1));
+      DISPATCH();
+    }
+
     OPCODE(PUSH_LIST):
     {
       List* list = newList(vm, (uint32_t)READ_SHORT());

src/libs/std_io.c

@@ -407,6 +407,7 @@ DEF(_fileTell, "") {
 // from io import File
 // return File().open(path, mode)
 DEF(_open, NULL /* == _fileOpen */) {
+  pkReserveSlots(vm, 3);
 
   // slots[1] = path
   // slots[2] = mode

tests/lang/controlflow.pk

@@ -71,5 +71,11 @@ end
 assert(val == 'bar')
 
 
+def test_in_local()
+  if x = fn y = false; return not y end ()
+    assert(x == true)
+  end
+end
+
 # If we got here, that means all test were passed.
 print('All TESTS PASSED')

tests/modules/io.File.pk

@@ -0,0 +1,26 @@
+
+from io import File
+from path import join, dirname
+
+FILE_PATH = join(dirname(__file__), 'test_file.txt')
+
+def read_file()
+  f = open(FILE_PATH)
+
+  assert(f is File)
+
+  LINES = [
+    'line1 : foo\n',
+    'line2 : bar\n',
+    'line3 : baz\n',
+    'line4 : qux\n',
+  ]
+
+  while line = f.getline()
+    assert(line in LINES)
+  end
+
+  f.close()
+end
+
+read_file()

tests/modules/test_file.txt

@@ -0,0 +1,4 @@
+line1 : foo
+line2 : bar
+line3 : baz
+line4 : qux