[mlir][AsmParser] Expose parseMinus() (llvm#106881)

Found while working on parser for custom expression type for my dialect.

Builtin `AffineExpr` uses low-level parser API which is not available
for external users.

Author: Hardcode84

mlir/include/mlir/IR/OpImplementation.h

@@ -641,6 +641,12 @@ class AsmParser {
   /// Parse a '+' token if present.
   virtual ParseResult parseOptionalPlus() = 0;
 
+  /// Parse a '-' token.
+  virtual ParseResult parseMinus() = 0;
+
+  /// Parse a '-' token if present.
+  virtual ParseResult parseOptionalMinus() = 0;
+
   /// Parse a '*' token.
   virtual ParseResult parseStar() = 0;
 

mlir/lib/AsmParser/AsmParserImpl.h

@@ -226,6 +226,16 @@ class AsmParserImpl : public BaseT {
     return success(parser.consumeIf(Token::plus));
   }
 
+  /// Parses a '-' token.
+  ParseResult parseMinus() override {
+    return parser.parseToken(Token::minus, "expected '-'");
+  }
+
+  /// Parses a '-' token if present.
+  ParseResult parseOptionalMinus() override {
+    return success(parser.consumeIf(Token::minus));
+  }
+
   /// Parse a '|' token.
   ParseResult parseVerticalBar() override {
     return parser.parseToken(Token::vertical_bar, "expected '|'");