From 39f848a431c95aaa11cab5727b48a85bc9f229be Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sun, 28 Aug 2022 14:20:22 -0700
Subject: [PATCH] str: New functions for case-matching of substrings, prefixes,
 and suffixes.

---
 src/libpspp/str.c | 32 ++++++++++++++++++++++++++++++++
 src/libpspp/str.h |  3 +++
 2 files changed, 35 insertions(+)

diff --git a/src/libpspp/str.c b/src/libpspp/str.c
index 811674225c..2a592b9064 100644
--- a/src/libpspp/str.c
+++ b/src/libpspp/str.c
@@ -615,6 +615,21 @@ ss_match_string (struct substring *ss, const struct substring target)
     return false;
 }
 
+/* If SS begins with TARGET, except possibly for case differences, removes it
+   and returns true.  Otherwise, returns false without changing SS. */
+bool
+ss_match_string_case (struct substring *ss, const struct substring target)
+{
+  size_t length = ss_length (target);
+  if (ss_equals_case (ss_head (*ss, length), target))
+    {
+      ss_advance (ss, length);
+      return true;
+    }
+  else
+    return false;
+}
+
 /* Removes the first byte from SS and returns it.
    If SS is empty, returns EOF without modifying SS. */
 int
@@ -743,6 +758,14 @@ ss_starts_with (struct substring ss, struct substring prefix)
           && !memcmp (ss.string, prefix.string, prefix.length));
 }
 
+/* Returns true if SS starts with PREFIX in any case, false otherwise. */
+bool
+ss_starts_with_case (struct substring ss, struct substring prefix)
+{
+  return (ss.length >= prefix.length
+          && !memcasecmp (ss.string, prefix.string, prefix.length));
+}
+
 /* Returns true if SS ends with SUFFIX, false otherwise. */
 bool
 ss_ends_with (struct substring ss, struct substring suffix)
@@ -752,6 +775,15 @@ ss_ends_with (struct substring ss, struct substring suffix)
                       suffix.length));
 }
 
+/* Returns true if SS ends with SUFFIX in any case, false otherwise. */
+bool
+ss_ends_with_case (struct substring ss, struct substring suffix)
+{
+  return (ss.length >= suffix.length
+          && !memcasecmp (&ss.string[ss.length - suffix.length], suffix.string,
+                          suffix.length));
+}
+
 /* Returns the number of contiguous bytes at the beginning
    of SS that are in SKIP_SET. */
 size_t
diff --git a/src/libpspp/str.h b/src/libpspp/str.h
index 91de05f395..c40915d939 100644
--- a/src/libpspp/str.h
+++ b/src/libpspp/str.h
@@ -118,6 +118,7 @@ void ss_advance (struct substring *, size_t);
 bool ss_match_byte (struct substring *, char);
 int ss_match_byte_in (struct substring *, struct substring);
 bool ss_match_string (struct substring *, const struct substring);
+bool ss_match_string_case (struct substring *, const struct substring);
 int ss_get_byte (struct substring *);
 size_t ss_get_bytes (struct substring *, size_t n, struct substring *);
 bool ss_get_until (struct substring *, char delimiter, struct substring *);
@@ -132,7 +133,9 @@ int ss_at (struct substring, size_t idx);
 int ss_first (struct substring);
 int ss_last (struct substring);
 bool ss_starts_with (struct substring, struct substring prefix);
+bool ss_starts_with_case (struct substring, struct substring prefix);
 bool ss_ends_with (struct substring, struct substring suffix);
+bool ss_ends_with_case (struct substring, struct substring suffix);
 size_t ss_span (struct substring, struct substring skip_set);
 size_t ss_cspan (struct substring, struct substring stop_set);
 size_t ss_find_byte (struct substring, char);
-- 
2.30.2