[llvm][ADT] Add llvm::StringRef::consume_front(char) overload #172832
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This patch adds support for consuming a `char` from the front of a `StringRef`. Most of the time a user wanting to consume a single character off the front can just wrap the character in a string literal (i.e., `consume_front("a")`). But this doesn't work if we don't have a `char` literal, but instead a variable of type `char`. I.e., `char c = 'a'; str.consume_front(c)`. This patch adds the `char` overload. We already have a `starts_with(char)` overload, so there's at least some related precedent.
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@llvm/pr-subscribers-llvm-adt Author: Michael Buch (Michael137) ChangesThis patch adds support for consuming a Full diff: https://github.com/llvm/llvm-project/pull/172832.diff 2 Files Affected:
diff --git a/llvm/include/llvm/ADT/StringRef.h b/llvm/include/llvm/ADT/StringRef.h
index 7aee2aa67ddec..2f85bb1aefdb0 100644
--- a/llvm/include/llvm/ADT/StringRef.h
+++ b/llvm/include/llvm/ADT/StringRef.h
@@ -632,6 +632,17 @@ namespace llvm {
return substr(find_if(F));
}
+ /// Returns true if this StringRef has the given prefix and removes that
+ /// prefix.
+ bool consume_front(char Prefix) {
+ if (!starts_with(Prefix))
+ return false;
+
+ *this = drop_front();
+
+ return true;
+ }
+
/// Returns true if this StringRef has the given prefix and removes that
/// prefix.
bool consume_front(StringRef Prefix) {
diff --git a/llvm/unittests/ADT/StringRefTest.cpp b/llvm/unittests/ADT/StringRefTest.cpp
index 1ace29e96dbb8..888cef9937e73 100644
--- a/llvm/unittests/ADT/StringRefTest.cpp
+++ b/llvm/unittests/ADT/StringRefTest.cpp
@@ -391,6 +391,26 @@ TEST(StringRefTest, ConsumeFront) {
EXPECT_TRUE(Str.consume_front(""));
}
+TEST(StringRefTest, ConsumeFrontChar) {
+ {
+ StringRef Str("hello");
+ EXPECT_EQ("hello", Str);
+ EXPECT_TRUE(Str.consume_front('h'));
+ EXPECT_EQ("ello", Str);
+ EXPECT_FALSE(Str.consume_front('h'));
+ EXPECT_EQ("ello", Str);
+ }
+
+ {
+ char Prefix = 'h';
+ StringRef Str("h");
+ EXPECT_TRUE(Str.consume_front(Prefix));
+ EXPECT_EQ("", Str);
+ EXPECT_FALSE(Str.consume_front('\0'));
+ EXPECT_EQ("", Str);
+ }
+}
+
TEST(StringRefTest, ConsumeFrontInsensitive) {
StringRef Str("heLLo");
EXPECT_TRUE(Str.consume_front_insensitive(""));
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tgymnich
reviewed
Dec 18, 2025
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Author
Do people prefer landing them together or is it ok to do this incrementally? |
Member
|
Either should be fine. |
Member
Author
Sounds good! I'd prefer implementing them separately then to aid reviewability |
tgymnich
approved these changes
Dec 19, 2025
kuhar
approved these changes
Dec 19, 2025
Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/27/builds/20566 Here is the relevant piece of the build log for the reference |
mahesh-attarde
pushed a commit
to mahesh-attarde/llvm-project
that referenced
this pull request
Dec 19, 2025
…72832) This patch adds support for consuming a `char` from the front of a `StringRef`. Most of the time a user wanting to consume a single character off the front can just wrap the character in a string literal (i.e., `consume_front("a")`). But this doesn't work if we don't have a `char` literal, but instead a variable of type `char`. I.e., `char c = 'a'; str.consume_front(c)`. There's at least one helper in LLDB that does this. Also there's plenty of example of `consume_front` being passed a single character via string literal. This patch adds the `char` overload. We already have a `starts_with(char)` overload, so there's at least some related precedent.
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This patch adds support for consuming a
charfrom the front of aStringRef. Most of the time a user wanting to consume a single character off the front can just wrap the character in a string literal (i.e.,consume_front("a")). But this doesn't work if we don't have acharliteral, but instead a variable of typechar. I.e.,char c = 'a'; str.consume_front(c). There's at least one helper in LLDB that does this. Also there's plenty of example ofconsume_frontbeing passed a single character via string literal. This patch adds thecharoverload. We already have astarts_with(char)overload, so there's at least some related precedent.