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

[via lldb-commits]

================
@@ -0,0 +1,356 @@
+//===-- 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 <limits.h>
+#include <stdlib.h>
+
+#include <memory>
+#include <sstream>
+#include <string>
+
+#include "lldb/Target/ExecutionContextScope.h"
+#include "lldb/ValueObject/DILAST.h"
+#include "lldb/ValueObject/DILEval.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/FormatAdapters.h"
+
+namespace lldb_private {
+
+namespace dil {
+
+inline void TokenKindsJoinImpl(std::ostringstream &os, dil::TokenKind k) {
+  os << "'" << DILToken::getTokenName(k) << "'";
+}
+
+template <typename... Ts>
+inline void TokenKindsJoinImpl(std::ostringstream &os, dil::TokenKind k,
+                               Ts... ks) {
+  TokenKindsJoinImpl(os, k);
+  os << ", ";
+  TokenKindsJoinImpl(os, ks...);
+}
+
+template <typename... Ts>
+inline std::string TokenKindsJoin(dil::TokenKind k, Ts... ks) {
+  std::ostringstream os;
+  TokenKindsJoinImpl(os, k, ks...);
+
+  return os.str();
+}
+
+std::string FormatDiagnostics(std::shared_ptr<std::string> input_expr,
+                              const std::string &message, uint32_t loc) {
+  // Get the source buffer and the location of the current token.
+  llvm::StringRef text(*input_expr);
+  size_t loc_offset = (size_t)loc;
+
+  // Look for the start of the line.
+  size_t line_start = text.rfind('\n', loc_offset);
+  line_start = line_start == llvm::StringRef::npos ? 0 : line_start + 1;
+
+  // Look for the end of the line.
+  size_t line_end = text.find('\n', loc_offset);
+  line_end = line_end == llvm::StringRef::npos ? text.size() : line_end;
+
+  // Get a view of the current line in the source code and the position of the
+  // diagnostics pointer.
+  llvm::StringRef line = text.slice(line_start, line_end);
+  int32_t arrow = loc + 1; // Column offset starts at 1, not 0.
+
+  // Calculate the padding in case we point outside of the expression (this can
+  // happen if the parser expected something, but got EOF).˚
+  size_t expr_rpad = std::max(0, arrow - static_cast<int32_t>(line.size()));
+  size_t arrow_rpad = std::max(0, static_cast<int32_t>(line.size()) - arrow);
+
+  return llvm::formatv("<expr:1:{0}>: {1}\n{2}\n{3}", loc, message,
+                       llvm::fmt_pad(line, 0, expr_rpad),
+                       llvm::fmt_pad("^", arrow - 1, arrow_rpad));
+}
+
+DILParser::DILParser(std::shared_ptr<std::string> 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)
+    : m_ctx_scope(exe_ctx_scope), m_input_expr(dil_input_expr),
+      m_use_dynamic(use_dynamic), m_use_synthetic(use_synthetic),
+      m_fragile_ivar(fragile_ivar), m_check_ptr_vs_member(check_ptr_vs_member),
+      m_dil_lexer(DILLexer(dil_input_expr)) {
+  // Initialize the token.
+  m_dil_token.setKind(dil::TokenKind::unknown);
+}
+
+DILASTNodeUP DILParser::Run(Status &error) {
+  ConsumeToken();
+
+  DILASTNodeUP expr;
+
+  expr = ParseExpression();
+
+  Expect(dil::TokenKind::eof);
+
+  error = std::move(m_error);
+  m_error.Clear();
+
+  // Explicitly return ErrorNode if there was an error during the parsing.
+  // Some routines raise an error, but don't change the return value (e.g.
+  // Expect).
+  if (error.Fail()) {
+    CompilerType bad_type;
+    return std::make_unique<ErrorNode>(bad_type);
+  }
+  return expr;
+}
+
+// Parse an expression.
+//
+//  expression:
+//    primary_expression
+//
+DILASTNodeUP DILParser::ParseExpression() { return ParsePrimaryExpression(); }
+
+// Parse a primary_expression.
+//
+//  primary_expression:
+//    id_expression
+//    "this"
+//    "(" expression ")"
+//
+DILASTNodeUP DILParser::ParsePrimaryExpression() {
+  CompilerType bad_type;
+  if (m_dil_token.isOneOf(dil::TokenKind::coloncolon,
+                          dil::TokenKind::identifier)) {
+    // Save the source location for the diagnostics message.
+    uint32_t loc = m_dil_token.getLocation();
+    auto identifier = ParseIdExpression();
+
+    return std::make_unique<IdentifierNode>(loc, identifier, m_use_dynamic,
+                                            m_ctx_scope);
+  } else if (m_dil_token.is(dil::TokenKind::kw_this)) {
+    // Save the source location for the diagnostics message.
+    uint32_t loc = m_dil_token.getLocation();
+    ConsumeToken();
+
+    // Special case for "this" pointer. As per C++ standard, it's a prvalue.
+    return std::make_unique<IdentifierNode>(loc, "this", m_use_dynamic,
+                                            m_ctx_scope);
+  } else if (m_dil_token.is(dil::TokenKind::l_paren)) {
+    ConsumeToken();
+    auto expr = ParseExpression();
+    Expect(dil::TokenKind::r_paren);
+    ConsumeToken();
+    return expr;
+  }
+
+  BailOut(ErrorCode::kInvalidExpressionSyntax,
+          llvm::formatv("Unexpected token: {0}", TokenDescription(m_dil_token)),
+          m_dil_token.getLocation());
+  return std::make_unique<ErrorNode>(bad_type);
+}
+
+// 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 (m_dil_token.isNot(dil::TokenKind::identifier) &&
+      m_dil_token.isNot(dil::TokenKind::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 (m_dil_token.is(dil::TokenKind::l_paren)) {
+    // Look for all the pieces, in order:
+    // l_paren 'anonymous' 'namespace' r_paren coloncolon
+    if (m_dil_lexer.LookAhead(0).is(dil::TokenKind::identifier) &&
+        (((DILToken)m_dil_lexer.LookAhead(0)).getSpelling() == "anonymous") &&
+        m_dil_lexer.LookAhead(1).is(dil::TokenKind::kw_namespace) &&
+        m_dil_lexer.LookAhead(2).is(dil::TokenKind::r_paren) &&
+        m_dil_lexer.LookAhead(3).is(dil::TokenKind::coloncolon)) {
+      m_dil_token = m_dil_lexer.AcceptLookAhead(3);
+
+      assert((m_dil_token.is(dil::TokenKind::identifier) ||
+              m_dil_token.is(dil::TokenKind::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(dil::TokenKind::identifier);
+        identifier2 = m_dil_token.getSpelling();
+        ConsumeToken();
+      }
+      return "(anonymous namespace)::" + identifier2;
+    } else {
+      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(0).is(dil::TokenKind::coloncolon)) {
+    // This nested_name_specifier is a single identifier.
+    std::string identifier = m_dil_token.getSpelling();
+    m_dil_token = m_dil_lexer.AcceptLookAhead(0);
+    Expect(dil::TokenKind::coloncolon);
+    ConsumeToken();
+    // 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:
+//    ? dil::TokenKind::identifier ?
+//
+std::string DILParser::ParseIdExpression() {
+  // Try parsing optional global scope operator.
+  bool global_scope = false;
+  if (m_dil_token.is(dil::TokenKind::coloncolon)) {
+    global_scope = true;
+    ConsumeToken();
+  }
+
+  // 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(dil::TokenKind::identifier);
+    std::string identifier = m_dil_token.getSpelling();
+    ConsumeToken();
+    return llvm::formatv("{0}{1}", global_scope ? "::" : "", identifier);
+  }
+
+  // This is unqualified_id production.
+  return ParseUnqualifiedId();
+}
+
+// Parse an unqualified_id.
+//
+//  unqualified_id:
+//    identifier
+//
+//  identifier:
+//    ? dil::TokenKind::identifier ?
+//
+std::string DILParser::ParseUnqualifiedId() {
+  Expect(dil::TokenKind::identifier);
+  std::string identifier = m_dil_token.getSpelling();
+  ConsumeToken();
+  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));
+  m_dil_token.setKind(dil::TokenKind::eof);
+}
+
+void DILParser::BailOut(Status error) {
+  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 = std::move(error);
+  m_dil_token.setKind(dil::TokenKind::eof);
+}
+
+void DILParser::ConsumeToken() {
+  if (m_dil_token.is(dil::TokenKind::eof)) {
+    // Don't do anything if we're already at eof. This can happen if an error
+    // occurred during parsing and we're trying to bail out.
+    return;
+  }
+  bool all_ok;
+  m_dil_lexer.Lex(m_dil_token);
+  if (m_dil_lexer.GetCurrentTokenIdx() == UINT_MAX)
+    all_ok = m_dil_lexer.ResetTokenIdx(0);
+  else
+    all_ok = m_dil_lexer.IncrementTokenIdx();
+  if (!all_ok)
+    BailOut(ErrorCode::kUnknown, "Invalid lexer token index", 0);
+}
+
+void DILParser::Expect(dil::TokenKind kind) {
+  if (m_dil_token.isNot(kind)) {
+    BailOut(ErrorCode::kUnknown,
+            llvm::formatv("expected {0}, got: {1}", TokenKindsJoin(kind),
+                          TokenDescription(m_dil_token)),
+            m_dil_token.getLocation());
+  }
+}
+
+template <typename... Ts>
+void DILParser::ExpectOneOf(dil::TokenKind k, Ts... ks) {
----------------
cmtice wrote:

Ah yes.. I missed that one (sorry); it is used in a later (more complex) version of the parser.

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