Changeset 99 for branches/interpreter/Parser3.pas

Timestamp:

Feb 6, 2017, 12:11:54 AM (8 years ago)

Author:

chronos

Message:

• Modified: Better parsing of expression and commands.

File:

• branches/interpreter/Parser3.pas (modified) (12 diffs)

branches/interpreter/Parser3.pas

@@ -27 +27 @@
 function ParseExecution(Execution: PExecution): Boolean; forward;
 function ParseBeginEnd(BeginEnd: PBeginEnd): Boolean; forward;
+function ParseGetValue(GetValue: PGetValue): Boolean; forward;
 
 
@@ -165 +166 @@
 end;
 
+function ParseConstant(out Constant: PConstant): Boolean;
+var
+  OldPos: Integer;
+  Next: string;
+begin
+  OldPos := InputTextPos;
+  Next := ReadNext;
+  Constant := MainProgram^.Constants.GetByName(Next);
+  if Constant <> nil then begin
+    Result := True;
+  end else begin
+    Result := False;
+    InputTextPos := OldPos;
+  end;
+end;
+
 function ParseExpression(Expression: PExpression): Boolean;
 var
@@ -170 +187 @@
   OldPos: Integer;
   R: Boolean;
+  GetValue: TGetValue;
+  Execution: TExecution;
   Variable: PVariable;
   SubExpression: TExpression;
-  Execution: TExecution;
 begin
   Result := True;
@@ -180 +198 @@
   if CheckNext('(') then begin
     Expect('(');
-    R := ParseExpression(@SubExpression);
+    if ParseGetValue(@GetValue) then begin
+      SetLength(Expression^.Items, Length(Expression^.Items) + 1);
+      Expression^.Items[Length(Expression^.Items) - 1] := GetValue;
+    end;
     Expect(')');
   end else
@@ -207 +228 @@
 end;
 
+function ParseGetValue(GetValue: PGetValue): Boolean;
+var
+  Variable: PVariable;
+  Constant: PConstant;
+  FunctionCall: TExecution;
+  Expression: TExpression;
+begin
+  if ParseVariable(Variable) then begin
+    GetValue^.Variable := Variable;
+    GetValue^.ReadType := rtVariable;
+  end else
+  if ParseConstant(Constant) then begin
+    GetValue^.Constant := Constant;
+    GetValue^.ReadType := rtConstant;
+  end else
+  if ParseExecution(@FunctionCall) then begin
+    GetValue^.FunctionCall := GetMem(SizeOf(TExecution));
+    GetValue^.FunctionCall^ := FunctionCall;
+    GetValue^.ReadType := rtFunctionCall;
+  end else
+  if ParseExpression(@Expression) then begin
+    GetValue^.Expression := GetMem(SizeOf(TExpression));
+    GetValue^.Expression^ := Expression;
+    GetValue^.ReadType := rtExpression;
+  end else
+    ShowError('Expected value');
+end;
+
 function ParseAssignment: Boolean;
 var
@@ -216 +265 @@
     Assignment.Destination := Variable;
     Expect(':=');
-    ParseExpression(@Assignment.Source);
+    ParseGetValue(@Assignment.Source);
   end else begin
     Result := False;
@@ -228 +277 @@
   Func: PFunction;
   I: Integer;
-  Expression: TExpression;
 begin
   Result := True;
@@ -235 +283 @@
   Func := MainProgram.Functions.GetByName(Next);
   if Func <> nil then begin
+    SetLength(Execution^.Parameters.Items, Length(Func^.Parameters.Items));
     if Length(Func^.Parameters.Items) > 0 then begin
       Expect('(');
       I := 0;
       while I < Length(Func^.Parameters.Items) do begin
-        ParseExpression(@Expression);
+        ParseGetValue(@Execution^.Parameters.Items[I]);
         if I < (Length(Func^.Parameters.Items) - 1) then Expect(',');
         I := I + 1;
@@ -251 +300 @@
 end;
 
-function ParseCommand: Boolean;
+function ParseCommand(Command: PCommand): Boolean;
 var
   IfThenElse: TIfThenElse;
@@ -257 +306 @@
   BeginEnd: TBeginEnd;
   Execution: TExecution;
+  Assignment: TAssignment;
 begin
   Result := True;
   if ParseBeginEnd(@BeginEnd) then begin
+    Command^.BeginEnd := GetMem(SizeOf(TBeginEnd));
+    Command^.BeginEnd^ := BeginEnd;
+    Command^.CmdType := ctBeginEnd;
   end else
   if ParseAssignment then begin
+    Command^.Assignment := GetMem(SizeOf(TAssignment));
+    Command^.Assignment^ := Assignment;
+    Command^.CmdType := ctAssignment;
   end else
   if ParseExecution(@Execution) then begin
+    Command^.Execution := GetMem(SizeOf(TExecution));
+    Command^.Execution^ := Execution;
+    Command^.CmdType := ctExecution;
   end else
   if ParseIfThen(@IfThenElse) then begin
+    Command^.IfThenElse := GetMem(SizeOf(TIfThenElse));
+    Command^.IfThenElse^ := IfThenElse;
+    Command^.CmdType := ctIfThenElse;
   end else
   if ParseWhileDo(@WhileDo) then begin
+    Command^.WhileDo := GetMem(SizeOf(TWhileDo));
+    Command^.WhileDo^ := WhileDo;
+    Command^.CmdType := ctWhileDo;
   end else Result := False;
 end;
@@ -278 +343 @@
     ParseExpression(@IfThenElse.Condition);
     Expect('then');
-    ParseCommand;
+    ParseCommand(@IfThenElse^.DoThen);
     if CheckNext('else') then begin
       Expect('else');
-      ParseCommand;
+      ParseCommand(@IfThenElse^.DoElse);
     end;
   end else Result := False;
@@ -293 +358 @@
     ParseExpression(@WhileDo.Condition);
     Expect('do');
-    ParseCommand;
+    ParseCommand(@WhileDo^.Command);
   end else Result := False;
 end;
 
 function ParseBeginEnd(BeginEnd: PBeginEnd): Boolean;
+var
+  Command: TCommand;
 begin
   if CheckNext('begin') then begin
     Result := True;
     Expect('begin');
+    SetLength(BeginEnd^.Commands, 0);
     repeat
-      if ParseCommand then begin
+      if ParseCommand(@Command) then begin
+        BeginEnd^.Add;
+        BeginEnd^.GetLast^ := Command;
         Expect(';');
       end else