Add parsing for attributes and attibutes on operations.  Add IR representation
for attributes on operations.  Split Operation out from OperationInst so it
can be shared with OperationStmt one day.

PiperOrigin-RevId: 203325366
diff --git a/lib/IR/AsmPrinter.cpp b/lib/IR/AsmPrinter.cpp
index b24eb2f..1cefc0a 100644
--- a/lib/IR/AsmPrinter.cpp
+++ b/lib/IR/AsmPrinter.cpp
@@ -22,6 +22,7 @@
 
 #include "mlir/IR/AffineExpr.h"
 #include "mlir/IR/AffineMap.h"
+#include "mlir/IR/Attributes.h"
 #include "mlir/IR/CFGFunction.h"
 #include "mlir/IR/MLFunction.h"
 #include "mlir/IR/Module.h"
@@ -32,6 +33,14 @@
 using namespace mlir;
 
 
+void Identifier::print(raw_ostream &os) const {
+  os << str();
+}
+
+void Identifier::dump() const {
+  print(llvm::errs());
+}
+
 //===----------------------------------------------------------------------===//
 // Function printing
 //===----------------------------------------------------------------------===//
@@ -140,7 +149,18 @@
 
 void CFGFunctionState::print(const OperationInst *inst) {
   // TODO: escape name if necessary.
-  os << "  \"" << inst->getName().str() << "\"()\n";
+  os << "  \"" << inst->getName().str() << "\"()";
+
+  auto attrs = inst->getAttrs();
+  if (!attrs.empty()) {
+    os << '{';
+    interleave(attrs, [&](NamedAttribute attr) {
+      os << attr.first << ": " << *attr.second;
+    }, [&]() { os << ", "; });
+    os << '}';
+  }
+
+  os << '\n';
 }
 
 void CFGFunctionState::print(const BranchInst *inst) {
diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp
index 0a773f1..df23424 100644
--- a/lib/IR/Attributes.cpp
+++ b/lib/IR/Attributes.cpp
@@ -38,15 +38,11 @@
     break;
   case Kind::Array: {
     auto elts = cast<ArrayAttr>(this)->getValue();
-    if (elts.empty())
-      os << "[]";
-    else {
-      os << "[ ";
-     interleave(elts,
-                 [&](Attribute *attr) { attr->print(os); },
-                 [&]() { os << ", "; });
-      os << " ]";
-    }
+    os << '[';
+    interleave(elts,
+                [&](Attribute *attr) { attr->print(os); },
+                [&]() { os << ", "; });
+    os << ']';
     break;
   }
   }
diff --git a/lib/IR/Operation.cpp b/lib/IR/Operation.cpp
new file mode 100644
index 0000000..f157169
--- /dev/null
+++ b/lib/IR/Operation.cpp
@@ -0,0 +1,40 @@
+//===- Operation.cpp - MLIR Operation Class -------------------------------===//
+//
+// Copyright 2019 The MLIR Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// =============================================================================
+
+#include "mlir/IR/Operation.h"
+using namespace mlir;
+
+Operation::Operation(Identifier name, ArrayRef<NamedAttribute> attrs)
+  : name(name), attrs(attrs.begin(), attrs.end()) {
+#ifndef NDEBUG
+  for (auto elt : attrs)
+    assert(elt.second != nullptr && "Attributes cannot have null entries");
+#endif
+}
+
+Operation::~Operation() {
+}
+
+auto Operation::removeAttr(Identifier name) -> RemoveResult {
+  for (unsigned i = 0, e = attrs.size(); i != e; ++i) {
+    if (attrs[i].first == name) {
+      attrs.erase(attrs.begin()+i);
+      return RemoveResult::Removed;
+    }
+  }
+  return RemoveResult::NotFound;
+}