[review] Add a string_view version of startswith

Christian Biesinger (Code Review)
2019-10-16T12:39:18Z

Christian Biesinger has uploaded a new change for review.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/126
......................................................................

Add a string_view version of startswith

Makes sure that the string is longer than prefix, so that strncmp will
do the right thing even if the string is not null-terminated.

For use in my string_view conversion patch:
https://sourceware.org/ml/gdb-patches/2019-10/msg00030.html

gdb/ChangeLog:

2019-10-01 Christian Biesinger <cbiesinger@google.com>

* gdbsupport/common-utils.h (startswith): Add an overloaded version
that takes gdb::string_view arguments.

Change-Id: I5389855de2fd70e7065a789a79374b0693651b71
---
M gdb/gdbsupport/common-utils.h
1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/gdb/gdbsupport/common-utils.h b/gdb/gdbsupport/common-utils.h
index a5312cb..e76b5b8 100644
--- a/gdb/gdbsupport/common-utils.h
+++ b/gdb/gdbsupport/common-utils.h
@@ -23,6 +23,7 @@
#include <string>
#include <vector>

+#include "gdb_string_view.h"
#include "poison.h"

/* If possible, define FUNCTION_NAME, a macro containing the name of
@@ -110,15 +111,25 @@

extern char *safe_strerror (int);

-/* Return non-zero if the start of STRING matches PATTERN, zero
+/* Return true if the start of STRING matches PATTERN, false
otherwise. */

-static inline int
+static inline bool
startswith (const char *string, const char *pattern)
{
return strncmp (string, pattern, strlen (pattern)) == 0;
}

+/* Version of startswith that takes string_view arguments. See comment
+ above. */
+
+static inline bool
+startswith (gdb::string_view string, gdb::string_view pattern)
+{
+ return (string.length () >= pattern.length ()
+ && strncmp (string.data (), pattern.data (), pattern.length ()) == 0);
+}
+
ULONGEST strtoulst (const char *num, const char **trailer, int base);

/* Skip leading whitespace characters in INP, returning an updated