Fix scan failures on immediately-terminated multiline comments

There's a bug in the lookahead for multiline comments where the first
character inside the comment is discarded. The effect is that an
immediately-terminated comment will erroneously consume input until it
finds another terminator.

Author: cirras

delphi-frontend/src/main/antlr3/au/com/integradev/delphi/antlr/Delphi.g

@@ -184,7 +184,7 @@ package au.com.integradev.delphi.antlr;
         "if".equalsIgnoreCase(directiveName) || "elseif".equalsIgnoreCase(directiveName);
 
     while (true) {
-      int character = input.LA(++i);
+      int character = input.LA(i);
 
       if (character == endStart) {
         int j;
@@ -234,6 +234,8 @@ package au.com.integradev.delphi.antlr;
         default:
           // do nothing
       }
+
+      ++i;
     }
   }
 

delphi-frontend/src/main/java/au/com/integradev/delphi/preprocessor/directive/expression/ExpressionLexer.java

@@ -364,7 +364,7 @@ private int lookaheadMultilineComment(String end, int i) {
         "if".equalsIgnoreCase(directiveName) || "elseif".equalsIgnoreCase(directiveName);
 
     while (true) {
-      int character = peekChar(++i);
+      int character = peekChar(i);
 
       if (character == endStart) {
         int j;
@@ -409,6 +409,8 @@ private int lookaheadMultilineComment(String end, int i) {
         default:
           // do nothing
       }
+
+      ++i;
     }
   }
 

delphi-frontend/src/test/java/au/com/integradev/delphi/antlr/GrammarTest.java

@@ -338,4 +338,9 @@ void testUnterminatedCommentShouldThrow() {
         .hasCauseInstanceOf(DelphiLexer.LexerException.class)
         .hasMessageContaining("line 7:0 unterminated multi-line comment");
   }
+
+  @Test
+  void testImmediatelyTerminatedComments() {
+    assertParsed("ImmediatelyTerminatedComments.pas");
+  }
 }

delphi-frontend/src/test/resources/au/com/integradev/delphi/grammar/ImmediatelyTerminatedComments.pas

@@ -0,0 +1,11 @@
+unit ImmediatelyTerminatedComments;
+
+interface
+
+implementation
+
+//
+{}
+(**)
+
+end.

delphi-frontend/src/test/resources/au/com/integradev/delphi/preprocessor/Expressions.pas

@@ -14,17 +14,17 @@ implementation
 {$endif}
 
 {$if
-  123 // }
-  = { }
-  321 (* } *)
+  123 //}
+  = {}
+  321 (*}*)
 }
 {$endif}
 
 {$if
   {$if
-    123 // }
-    = { }
-    321 (* } *)
+    123 //}
+    = {}
+    321 (*}*)
   }
   {$endif}
 }