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

[via lldb-commits]

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+//===-- DILLexer.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/DILLexer.h"
+
+namespace lldb_private {
+
+namespace dil {
+
+const std::string DILToken::getTokenName(dil::TokenKind kind) {
+  std::string retval;
+  switch (kind) {
+  case dil::TokenKind::coloncolon:
+    retval = "coloncolon";
+    break;
+  case dil::TokenKind::eof:
+    retval = "eof";
+    break;
+  case dil::TokenKind::identifier:
+    retval = "identifier";
+    break;
+  case dil::TokenKind::kw_namespace:
+    retval = "namespace";
+    break;
+  case dil::TokenKind::kw_this:
+    retval = "this";
+    break;
+  case dil::TokenKind::l_paren:
+    retval = "l_paren";
+    break;
+  case dil::TokenKind::r_paren:
+    retval = "r_paren";
+    break;
+  case dil::TokenKind::unknown:
+    retval = "unknown";
+    break;
+  default:
+    retval = "token_name";
+    break;
+  }
+  return retval;
+}
+
+static bool Is_Letter(char c) {
+  if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z'))
+    return true;
+  return false;
+}
+
+static bool Is_Digit(char c) { return ('0' <= c && c <= '9'); }
+
+bool DILLexer::Is_Word(std::string::iterator start, uint32_t &length) {
+  bool done = false;
+  for (; m_cur_pos != m_expr.end() && !done; ++m_cur_pos) {
+    char c = *m_cur_pos;
+    if (!Is_Letter(c) && !Is_Digit(c) && c != '_') {
+      done = true;
+      break;
+    } else
+      length++;
+  }
+  if (length > 0)
+    return true;
+  else
+    m_cur_pos = start;
+  return false;
+}
+
+void DILLexer::UpdateLexedTokens(DILToken &result, dil::TokenKind tok_kind,
+                                 std::string tok_str, uint32_t tok_pos,
+                                 uint32_t tok_len) {
+  DILToken new_token;
+  result.setValues(tok_kind, tok_str, tok_pos, tok_len);
+  new_token = result;
+  m_lexed_tokens.push_back(std::move(new_token));
+}
+
+bool DILLexer::Lex(DILToken &result, bool look_ahead) {
+  bool retval = true;
+
+  if (!look_ahead) {
+    // We're being asked for the 'next' token, and not a part of a LookAhead.
+    // Check to see if we've already lexed it and pushed it onto our tokens
+    // vector; if so, return the next token from the vector, rather than doing
+    // more lexing.
+    if ((m_tokens_idx != UINT_MAX) &&
+        (m_tokens_idx < m_lexed_tokens.size() - 1)) {
+      result = m_lexed_tokens[m_tokens_idx + 1];
+      return retval;
+    }
+  }
+
+  // Skip over whitespace (spaces).
+  while (m_cur_pos != m_expr.end() && *m_cur_pos == ' ')
+    m_cur_pos++;
+
+  // Check to see if we've reached the end of our input string.
+  if (m_cur_pos == m_expr.end()) {
+    UpdateLexedTokens(result, dil::TokenKind::eof, "", m_expr.length(), 0);
+    return retval;
+  }
+
+  uint32_t position = m_cur_pos - m_expr.begin();
+  ;
+  std::string::iterator start = m_cur_pos;
+  uint32_t length = 0;
+  if (Is_Word(start, length)) {
+    dil::TokenKind kind;
+    std::string word = m_expr.substr(position, length);
+    if (word == "this")
+      kind = dil::TokenKind::kw_this;
+    else if (word == "namespace")
+      kind = dil::TokenKind::kw_namespace;
+    else
+      kind = dil::TokenKind::identifier;
+
+    UpdateLexedTokens(result, kind, word, position, length);
+    return true;
+  }
+
+  switch (*m_cur_pos) {
+  case '(':
+    m_cur_pos++;
+    UpdateLexedTokens(result, dil::TokenKind::l_paren, "(", position, 1);
+    return true;
+  case ')':
+    m_cur_pos++;
+    UpdateLexedTokens(result, dil::TokenKind::r_paren, ")", position, 1);
+    return true;
+  case ':':
+    if (position + 1 < m_expr.size() && m_expr[position + 1] == ':') {
+      m_cur_pos += 2;
+      UpdateLexedTokens(result, dil::TokenKind::coloncolon, "::", position, 2);
+      return true;
+    }
+    break;
+  default:
+    break;
+  }
+  // Empty Token
+  result.setValues(dil::TokenKind::none, "", m_expr.length(), 0);
+  return false;
+}
+
+const DILToken &DILLexer::LookAhead(uint32_t N) {
+  uint32_t extra_lexed_tokens = m_lexed_tokens.size() - m_tokens_idx - 1;
+
+  if (N + 1 < extra_lexed_tokens)
+    return m_lexed_tokens[m_tokens_idx + N + 1];
+
+  uint32_t remaining_tokens =
+      (m_tokens_idx + N + 1) - m_lexed_tokens.size() + 1;
+
+  bool done = false;
+  bool look_ahead = true;
+  while (!done && remaining_tokens > 0) {
+    DILToken tok;
+    Lex(tok, look_ahead);
+    if (tok.getKind() == dil::TokenKind::eof)
+      done = true;
+    remaining_tokens--;
+  };
+
+  if (remaining_tokens > 0) {
+    m_invalid_token.setValues(dil::TokenKind::invalid, "", 0, 0);
+    return m_invalid_token;
+  } else
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cmtice wrote:

Done.

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