================
@@ -0,0 +1,132 @@
+//===-- 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"
+#include "lldb/Utility/Status.h"
+#include "llvm/ADT/StringSwitch.h"
+
+namespace lldb_private::dil {
+
+llvm::StringRef Token::GetTokenName(Kind kind) {
+ switch (kind) {
+ case Kind::coloncolon:
+ return "coloncolon";
+ case Kind::eof:
+ return "eof";
+ case Kind::identifier:
+ return "identifier";
+ case Kind::l_paren:
+ return "l_paren";
+ case Kind::r_paren:
+ return "r_paren";
+ case Kind::unknown:
+ return "unknown";
+ }
+}
+
+static bool IsLetter(char c) {
+ return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z');
+}
+
+static bool IsDigit(char c) { return '0' <= c && c <= '9'; }
+
+// A word starts with a letter, underscore, or dollar sign, followed by
+// letters ('a'..'z','A'..'Z'), digits ('0'..'9'), and/or underscores.
+static std::optional<llvm::StringRef> IsWord(llvm::StringRef expr,
+ llvm::StringRef &remainder) {
+ llvm::StringRef::iterator cur_pos = expr.end() - remainder.size();
+ llvm::StringRef::iterator start = cur_pos;
+ bool dollar_start = false;
+
+ // Must not start with a digit.
+ if (cur_pos == expr.end() || IsDigit(*cur_pos))
+ return std::nullopt;
+
+ // First character *may* be a '$', for a register name or convenience
+ // variable.
+ if (*cur_pos == '$') {
+ dollar_start = true;
+ ++cur_pos;
+ }
+
+ // Contains only letters, digits or underscores
+ for (; cur_pos != expr.end(); ++cur_pos) {
+ char c = *cur_pos;
+ if (!IsLetter(c) && !IsDigit(c) && c != '_')
+ break;
+ }
+
+ // If first char is '$', make sure there's at least one mare char, or it's
+ // invalid.
+ if (dollar_start && (cur_pos - start <= 1)) {
+ cur_pos = start;
+ return std::nullopt;
+ }
+
+ if (cur_pos == start)
+ return std::nullopt;
+
+ llvm::StringRef word = expr.substr(start - expr.begin(), cur_pos - start);
+ if (remainder.consume_front(word))
+ return word;
+
+ return std::nullopt;
----------------
labath wrote:
This should be equivalent to your code, but I'm only suggesting this to show
how code like this can be written in a shorter and more stringref-y fashion. I
think the actual algorithm will have to change, as it has a very narrow
definition of identifiers.
```suggestion
const char *start = remainder.data();
remainder.consume_front("$"); // initial '$' is valid
remainder = remainder.drop_while([](char c){ return IsDigit(c) ||
IsLetter(c) || c=='_'; });
llvm::StringRef candidate(start, remainder.data()-start);
if (candidate.empty() || candidate == "$" || IsDigit(candidate[0]))
return std::nullopt;
return candidate;
```
https://github.com/llvm/llvm-project/pull/123521
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