1 files changed, 92 insertions, 0 deletions
diff --git a/ext/misc/uint.c b/ext/misc/uint.c
new file mode 100644
index 0000000..286314f
--- /dev/null
+++ b/ext/misc/uint.c
@@ -0,0 +1,92 @@
+/*
+** 2020-04-14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This SQLite extension implements the UINT collating sequence.
+**
+** UINT works like BINARY for text, except that embedded strings
+** of digits compare in numeric order.
+**
+**     *   Leading zeros are handled properly, in the sense that
+**         they do not mess of the maginitude comparison of embedded
+**         strings of digits.  "x00123y" is equal to "x123y".
+**
+**     *   Only unsigned integers are recognized.  Plus and minus
+**         signs are ignored.  Decimal points and exponential notation
+**         are ignored.
+**
+**     *   Embedded integers can be of arbitrary length.  Comparison
+**         is *not* limited integers that can be expressed as a
+**         64-bit machine integer.
+*/
+#include "sqlite3ext.h"
+SQLITE_EXTENSION_INIT1
+#include <assert.h>
+#include <string.h>
+#include <ctype.h>
+
+/*
+** Compare text in lexicographic order, except strings of digits
+** compare in numeric order.
+*/
+static int uintCollFunc(
+  void *notUsed,
+  int nKey1, const void *pKey1,
+  int nKey2, const void *pKey2
+){
+  const unsigned char *zA = (const unsigned char*)pKey1;
+  const unsigned char *zB = (const unsigned char*)pKey2;
+  int i=0, j=0, x;
+  (void)notUsed;
+  while( i<nKey1 && j<nKey2 ){
+    x = zA[i] - zB[j];
+    if( isdigit(zA[i]) ){
+      int k;
+      if( !isdigit(zB[j]) ) return x;
+      while( i<nKey1 && zA[i]=='0' ){ i++; }
+      while( j<nKey2 && zB[j]=='0' ){ j++; }
+      k = 0;
+      while( i+k<nKey1 && isdigit(zA[i+k])
+             && j+k<nKey2 && isdigit(zB[j+k]) ){
+        k++;
+      }
+      if( i+k<nKey1 && isdigit(zA[i+k]) ){
+        return +1;
+      }else if( j+k<nKey2 && isdigit(zB[j+k]) ){
+        return -1;
+      }else{
+        x = memcmp(zA+i, zB+j, k);
+        if( x ) return x;
+        i += k;
+        j += k;
+      }
+    }else if( x ){
+      return x;
+    }else{
+      i++;
+      j++;
+    }
+  }
+  return (nKey1 - i) - (nKey2 - j);
+}
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int sqlite3_uint_init(
+  sqlite3 *db, 
+  char **pzErrMsg, 
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi);
+  (void)pzErrMsg;  /* Unused parameter */
+  return sqlite3_create_collation(db, "uint", SQLITE_UTF8, 0, uintCollFunc);
+}