Optimisations to log rendering with mustache

1 files changed, 49 insertions, 0 deletions

diff --git a/cbits/escapexml.c b/cbits/escapexml.c
new file mode 100644
index 0000000..6eb366d
--- /dev/null
+++ b/cbits/escapexml.c
@@ -0,0 +1,49 @@
+#include <string.h>
+#include <stdint.h>
+
+// https://hackage-content.haskell.org/package/mustache-2.4.3.1/src/src/Text/Mustache/Internal.hs
+//
+// escapeXML :: String -> String
+// escapeXML = concatMap $ \x -> IntMap.findWithDefault [x] (ord x) mp
+//     where mp = IntMap.fromList [(ord b, "&"++a++";") | (a,[b]) <- xmlEntities]
+//
+// xmlEntities :: [(String, String)]
+// xmlEntities =
+//   [ ("quot", "\"")
+//   , ("#39", "'")
+//   , ("amp" , "&")
+//   , ("lt"  , "<")
+//   , ("gt"  , ">")
+//   ]
+
+#define ENTITIES_XLIST \
+  X('"', 6, "&quot;") \
+  X('\'', 5, "&#39;") \
+  X('&', 5, "&amp;") \
+  X('<', 4, "&lt;") \
+  X('>', 4, "&gt;")
+
+size_t tirclogv_escapexml_len(const uint8_t *src, size_t src_off, size_t src_len) {
+  size_t reslen = 0;
+  for (size_t i = 0; i < src_len; i++) {
+    switch (src[src_off + i]) {
+#define X(ch, len, _str) case ch: reslen += len; break;
+      ENTITIES_XLIST
+#undef X
+      default: reslen += 1; break;
+    }
+  }
+  return reslen;
+}
+
+void tirclogv_escapexml(uint8_t *dst, const uint8_t *src, size_t src_off, size_t src_len) {
+  for (size_t i = 0, j = 0; i < src_len; i++) {
+    const uint8_t c = src[src_off + i];
+    switch (c) {
+#define X(ch, len, str) case ch: memcpy(&dst[j], str, len); j += len; break;
+      ENTITIES_XLIST
+#undef X
+      default: dst[j++] = c; break;
+    }
+  }
+}