Modified 1451.lp to test code to permit keywords as constraint names

check/TestFilereader.cpp

@@ -143,6 +143,8 @@ TEST_CASE("filereader-edge-cases", "[highs_filereader]") {
   REQUIRE(read_status == HighsStatus::kError);
 
   model = "1451";
+  // Vanilla .lp file, but for constraint named "end" which tests code
+  // to permit keywords as constraint names
   if (dev_run) printf("\n%s.lp\n", model.c_str());
   model_file = std::string(HIGHS_DIR) + "/check/instances/" + model + ".lp";
   read_status = highs.readModel(model_file);

check/instances/1451.lp

@@ -1,7 +1,8 @@
 Minimize
   x
 Subject to
-  x - 1 >= 2
+\ Name this constraint end to test for keywords as constraint names
+ end: x - 1 >= 2
 Integer
   x
 End

highs/io/filereaderlp/reader.cpp

@@ -55,6 +55,48 @@ enum class RawTokenType {
   ASTERISK
 };
 
+/*
+  // Useful for debugging
+static std::string tokenTypeToString(const RawTokenType& type) {
+  switch (type) {
+  case RawTokenType::NONE:
+    return "None";
+  case RawTokenType::STR:
+    return "String";
+  case RawTokenType::CONS:
+    return "Constraint ";
+  case RawTokenType::LESS:
+    return "<=";
+  case RawTokenType::GREATER:
+    return ">=";
+  case RawTokenType::EQUAL:
+    return "=";
+  case RawTokenType::COLON:
+    return ":";
+  case RawTokenType::LNEND:
+    return "\\n";
+  case RawTokenType::FLEND:
+    return "EOF";
+  case RawTokenType::BRKOP:
+    return "(";
+  case RawTokenType::BRKCL:
+    return ")";
+  case RawTokenType::PLUS:
+    return "+";
+  case RawTokenType::MINUS:
+    return "-";
+  case RawTokenType::HAT:
+    return "^";
+  case RawTokenType::SLASH:
+    return "/";
+  case RawTokenType::ASTERISK:
+    return "*";
+  default:
+    return "Unknown";
+  }
+}
+*/
+
 struct RawToken {
   RawTokenType type = RawTokenType::NONE;
   std::string svalue;
@@ -244,6 +286,7 @@ class Reader {
                        std::vector<ProcessedToken>::iterator end,
                        std::shared_ptr<Expression> expr, bool isobj);
 
+  //  void printRawTokens();
  public:
   Reader(std::string filename) {
 #ifdef ZLIB_FOUND
@@ -872,8 +915,13 @@ void Reader::splittokens() {
 void Reader::processtokens() {
   std::string svalue_lc;
   while (!rawtokens[0].istype(RawTokenType::FLEND)) {
-    fflush(stdout);
-
+    if (rawtokens[0].type == RawTokenType::STR) {
+      if (parsesectionkeyword(rawtokens[0].svalue) != LpSectionKeyword::NONE) {
+	// Found an LP section keyword so check it's not a constraint name!
+	if (rawtokens[1].type == RawTokenType::COLON)
+	  rawtokens[0].type = RawTokenType::CONS;
+      }
+    }
     // Slash + asterisk: comment, skip everything up to next asterisk + slash
     if (rawtokens[0].istype(RawTokenType::SLASH) &&
         rawtokens[1].istype(RawTokenType::ASTERISK)) {
@@ -1119,6 +1167,8 @@ void Reader::processtokens() {
     assert(!rawtokens[0].istype(RawTokenType::FLEND));
 
     // catch all unknown symbols
+    //
+    //    printRawTokens();
     lpassert(false);
     break;
   }
@@ -1309,3 +1359,17 @@ bool Reader::readnexttoken(RawToken& t) {
   lpassert(false);
   return false;
 }
+
+/*
+  // Useful for debugging
+void Reader::printRawTokens() {
+  for(int iToken=0; iToken < NRAWTOKEN; iToken++) {
+    const RawToken& rawtoken = rawtokens[iToken];
+    printf("rawtokens[%d]: ", int(iToken));
+    printf("type = %-12s", tokenTypeToString(rawtoken.type).c_str());
+    printf("; svalue = %8s: ", rawtoken.svalue.c_str());
+    if (iToken < NRAWTOKEN-1) printf("; ");
+  }
+  printf("\n");
+}
+*/