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

[Adrian Prantl via lldb-commits]

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@@ -0,0 +1,102 @@
+//===-- DILParser.h ---------------------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_VALUEOBJECT_DILPARSER_H_
+#define LLDB_VALUEOBJECT_DILPARSER_H_
+
+#include "lldb/Target/ExecutionContextScope.h"
+#include "lldb/Utility/Status.h"
+#include "lldb/ValueObject/DILAST.h"
+#include "lldb/ValueObject/DILLexer.h"
+#include <memory>
+#include <optional>
+#include <string>
+#include <tuple>
+#include <vector>
+
+namespace lldb_private {
+
+namespace dil {
+
+enum class ErrorCode : unsigned char {
+  kOk = 0,
+  kInvalidExpressionSyntax,
+  kUndeclaredIdentifier,
+  kUnknown,
+};
+
+std::string FormatDiagnostics(llvm::StringRef input_expr,
+                              const std::string &message, uint32_t loc);
+
+/// Pure recursive descent parser for C++ like expressions.
+/// EBNF grammar for the parser is described in lldb/docs/dil-expr-lang.ebnf
+class DILParser {
+public:
+  explicit DILParser(llvm::StringRef dil_input_expr,
+                     std::shared_ptr<ExecutionContextScope> exe_ctx_scope,
+                     lldb::DynamicValueType use_dynamic, bool use_synthetic,
+                     bool fragile_ivar, bool check_ptr_vs_member);
+
+  llvm::Expected<DILASTNodeUP> Run();
+
+  ~DILParser() { m_ctx_scope.reset(); }
+
+  bool UseSynthetic() { return m_use_synthetic; }
+
+  lldb::DynamicValueType UseDynamic() { return m_use_dynamic; }
+
+  using PtrOperator = std::tuple<dil::TokenKind, uint32_t>;
+
+private:
+  DILASTNodeUP ParseExpression();
+  DILASTNodeUP ParsePrimaryExpression();
+
+  std::string ParseNestedNameSpecifier();
+
+  std::string ParseIdExpression();
+  std::string ParseUnqualifiedId();
+
+  void ConsumeToken();
+
+  void BailOut(ErrorCode error_code, const std::string &error, uint32_t loc);
+
+  void BailOut(Status error);
+
+  void Expect(dil::TokenKind kind);
+
+  std::string TokenDescription(const DILToken &token);
+
+  void TentativeParsingRollback(uint32_t saved_idx) {
+    m_error.Clear();
+    m_dil_lexer.ResetTokenIdx(saved_idx);
+    m_dil_token = m_dil_lexer.GetCurrentToken();
+  }
+
+  // Parser doesn't own the evaluation context. The produced AST may depend on
+  // it (for example, for source locations), so it's expected that expression
+  // context will outlive the parser.
+  std::shared_ptr<ExecutionContextScope> m_ctx_scope;
+
+  llvm::StringRef m_input_expr;
+  // The token lexer is stopped at (aka "current token").
+  DILToken m_dil_token;
+  // Holds an error if it occures during parsing.
+  Status m_error;
----------------
adrian-prantl wrote:

Would it make sense to use a https://lldb.llvm.org/cpp_reference/classlldb__private_1_1DiagnosticManager.html here?
You can wrap diagnostics in an Error/Status

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