[Lldb-commits] [lldb] [LLDB] Add DIL code for handling plain variable names. (PR #120971)

[Pavel Labath via lldb-commits]

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@@ -0,0 +1,273 @@
+//===-- DILParser.cpp -----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// This implements the recursive descent parser for the Data Inspection
+// Language (DIL), and its helper functions, which will eventually underlie the
+// 'frame variable' command. The language that this parser recognizes is
+// described in lldb/docs/dil-expr-lang.ebnf
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/ValueObject/DILParser.h"
+#include "lldb/Target/ExecutionContextScope.h"
+#include "lldb/Utility/DiagnosticsRendering.h"
+#include "lldb/ValueObject/DILAST.h"
+#include "lldb/ValueObject/DILEval.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/FormatAdapters.h"
+#include <cstdlib>
+#include <limits.h>
+#include <memory>
+#include <sstream>
+#include <string>
+
+namespace lldb_private::dil {
+
+std::string FormatDiagnostics(llvm::StringRef text, const std::string &message,
+                              uint32_t loc, uint16_t err_len) {
+  DiagnosticDetail::SourceLocation sloc = {
+      FileSpec{}, /*line=*/1, static_cast<uint16_t>(loc + 1),
+      err_len,    false,      /*in_user_input=*/true};
+  std::string arrow_str = "^";
+  std::string rendered_msg =
+      llvm::formatv("<user expression 0>:1:{0}: {1}\n    1 | {2}\n     | ^",
+                    loc + 1, message, text);
+  DiagnosticDetail detail;
+  detail.source_location = sloc;
+  detail.severity = lldb::eSeverityError;
+  detail.message = message;
+  detail.rendered = rendered_msg;
+  std::vector<DiagnosticDetail> diagnostics;
+  diagnostics.push_back(detail);
+  StreamString diag_stream(true);
+  RenderDiagnosticDetails(diag_stream, 7, true, diagnostics);
+  std::string ret_str = text.str() + "\n" + diag_stream.GetString().str();
+  return ret_str;
+}
+
+llvm::Expected<ASTNodeUP>
+DILParser::Parse(llvm::StringRef dil_input_expr, DILLexer lexer,
+                 std::shared_ptr<StackFrame> frame_sp,
+                 lldb::DynamicValueType use_dynamic, bool use_synthetic,
+                 bool fragile_ivar, bool check_ptr_vs_member) {
+  Status error;
+  DILParser parser(dil_input_expr, lexer, frame_sp, use_dynamic, use_synthetic,
+                   fragile_ivar, check_ptr_vs_member, error);
+  return parser.Run();
+}
+
+DILParser::DILParser(llvm::StringRef dil_input_expr, DILLexer lexer,
+                     std::shared_ptr<StackFrame> frame_sp,
+                     lldb::DynamicValueType use_dynamic, bool use_synthetic,
+                     bool fragile_ivar, bool check_ptr_vs_member, Status &error)
+    : m_ctx_scope(frame_sp), m_input_expr(dil_input_expr), m_dil_lexer(lexer),
+      m_error(error), m_use_dynamic(use_dynamic),
+      m_use_synthetic(use_synthetic), m_fragile_ivar(fragile_ivar),
+      m_check_ptr_vs_member(check_ptr_vs_member) {}
+
+llvm::Expected<ASTNodeUP> DILParser::Run() {
+  ASTNodeUP expr = ParseExpression();
+
+  Expect(Token::Kind::eof);
+
+  if (m_error.Fail())
+    return m_error.ToError();
+
+  return expr;
+}
+
+// Parse an expression.
+//
+//  expression:
+//    primary_expression
+//
+ASTNodeUP DILParser::ParseExpression() { return ParsePrimaryExpression(); }
+
+// Parse a primary_expression.
+//
+//  primary_expression:
+//    id_expression
+//    "(" expression ")"
+//
+ASTNodeUP DILParser::ParsePrimaryExpression() {
+  if (CurToken().IsOneOf({Token::coloncolon, Token::identifier})) {
+    // Save the source location for the diagnostics message.
+    uint32_t loc = CurToken().GetLocation();
+    auto identifier = ParseIdExpression();
+
+    return std::make_unique<IdentifierNode>(loc, identifier, m_use_dynamic,
+                                            m_ctx_scope);
+  } else if (CurToken().Is(Token::l_paren)) {
+    m_dil_lexer.Advance();
+    auto expr = ParseExpression();
+    Expect(Token::r_paren);
+    m_dil_lexer.Advance();
+    return expr;
+  }
+
+  BailOut(ErrorCode::kInvalidExpressionSyntax,
+          llvm::formatv("Unexpected token: {0}", CurToken()),
+          CurToken().GetLocation());
+  return std::make_unique<ErrorNode>();
+}
+
+// Parse nested_name_specifier.
+//
+//  nested_name_specifier:
+//    type_name "::"
+//    namespace_name "::"
+//    nested_name_specifier identifier "::"
+//
+std::string DILParser::ParseNestedNameSpecifier() {
+  // The first token in nested_name_specifier is always an identifier, or
+  // '(anonymous namespace)'.
+  if (CurToken().IsNot(Token::identifier) && CurToken().IsNot(Token::l_paren)) {
+    return "";
+  }
+
+  // Anonymous namespaces need to be treated specially: They are represented
+  // the the string '(anonymous namespace)', which has a space in it (throwing
+  // off normal parsing) and is not actually proper C++> Check to see if we're
+  // looking at '(anonymous namespace)::...'
+  if (CurToken().Is(Token::l_paren)) {
+    // Look for all the pieces, in order:
+    // l_paren 'anonymous' 'namespace' r_paren coloncolon
+    if (m_dil_lexer.LookAhead(1).Is(Token::identifier) &&
+        (m_dil_lexer.LookAhead(1).GetSpelling() == "anonymous") &&
+        m_dil_lexer.LookAhead(2).Is(Token::identifier) &&
+        (m_dil_lexer.LookAhead(2).GetSpelling() == "namespace") &&
+        m_dil_lexer.LookAhead(3).Is(Token::r_paren) &&
+        m_dil_lexer.LookAhead(4).Is(Token::coloncolon)) {
+      m_dil_lexer.Advance(4);
+
+      assert(
+          (CurToken().Is(Token::identifier) || CurToken().Is(Token::l_paren)) &&
+          "Expected an identifier or anonymous namespace, but not found.");
+      // Continue parsing the nested_namespace_specifier.
+      std::string identifier2 = ParseNestedNameSpecifier();
+      if (identifier2.empty()) {
+        Expect(Token::identifier);
+        identifier2 = CurToken().GetSpelling();
+        m_dil_lexer.Advance();
+      }
+      return "(anonymous namespace)::" + identifier2;
+    }
+
+    return "";
+  } // end of special handling for '(anonymous namespace)'
+
+  // If the next token is scope ("::"), then this is indeed a
+  // nested_name_specifier
+  if (m_dil_lexer.LookAhead(1).Is(Token::coloncolon)) {
+    // This nested_name_specifier is a single identifier.
+    std::string identifier = CurToken().GetSpelling();
+    m_dil_lexer.Advance(1);
+    Expect(Token::coloncolon);
+    m_dil_lexer.Advance();
+    // Continue parsing the nested_name_specifier.
+    return identifier + "::" + ParseNestedNameSpecifier();
+  }
+
+  return "";
+}
+
+// Parse an id_expression.
+//
+//  id_expression:
+//    unqualified_id
+//    qualified_id
+//
+//  qualified_id:
+//    ["::"] [nested_name_specifier] unqualified_id
+//    ["::"] identifier
+//
+//  identifier:
+//    ? Token::identifier ?
+//
+std::string DILParser::ParseIdExpression() {
+  // Try parsing optional global scope operator.
+  bool global_scope = false;
+  if (CurToken().Is(Token::coloncolon)) {
+    global_scope = true;
+    m_dil_lexer.Advance();
+  }
+
+  // Try parsing optional nested_name_specifier.
+  auto nested_name_specifier = ParseNestedNameSpecifier();
+
+  // If nested_name_specifier is present, then it's qualified_id production.
+  // Follow the first production rule.
+  if (!nested_name_specifier.empty()) {
+    // Parse unqualified_id and construct a fully qualified id expression.
+    auto unqualified_id = ParseUnqualifiedId();
+
+    return llvm::formatv("{0}{1}{2}", global_scope ? "::" : "",
+                         nested_name_specifier, unqualified_id);
+  }
+
+  // No nested_name_specifier, but with global scope -- this is also a
+  // qualified_id production. Follow the second production rule.
+  else if (global_scope) {
+    Expect(Token::identifier);
+    std::string identifier = CurToken().GetSpelling();
+    m_dil_lexer.Advance();
+    return llvm::formatv("{0}{1}", global_scope ? "::" : "", identifier);
+  }
+
+  // This is unqualified_id production.
+  return ParseUnqualifiedId();
+}
+
+// Parse an unqualified_id.
+//
+//  unqualified_id:
+//    identifier
+//
+//  identifier:
+//    ? Token::identifier ?
+//
+std::string DILParser::ParseUnqualifiedId() {
+  Expect(Token::identifier);
+  std::string identifier = CurToken().GetSpelling();
+  m_dil_lexer.Advance();
+  return identifier;
+}
+
+void DILParser::BailOut(ErrorCode code, const std::string &error,
+                        uint32_t loc) {
+  if (m_error.Fail()) {
+    // If error is already set, then the parser is in the "bail-out" mode. Don't
+    // do anything and keep the original error.
+    return;
+  }
+
+  m_error = Status((uint32_t)code, lldb::eErrorTypeGeneric,
+                   FormatDiagnostics(m_input_expr, error, loc,
+                                     CurToken().GetSpelling().length()));
----------------
labath wrote:

```suggestion
  m_error = CreateDiagnosticError(code,
                   m_input_expr, error, loc,
                                     CurToken().GetSpelling().length()));
```

or something like that.

https://github.com/llvm/llvm-project/pull/120971