iter.c.diff

diff --git a/src/strings/iter.h b/src/strings/iter.h
index 21679304..2b7d8925 100644
--- a/src/strings/iter.h
+++ b/src/strings/iter.h
@@ -171,6 +171,35 @@ MVM_STATIC_INLINE void MVM_string_ci_init(MVMThreadContext *tc, MVMCodepointIter
     ci->synth_codes = NULL;
     ci->translate_newlines = translate_newlines;
 };
+/* Iterates on a grapheme. Returns the grapheme's base character. Can only be used on synthetics */
+MVM_STATIC_INLINE MVMGrapheme32 MVM_grapheme_ci_init(MVMThreadContext *tc, MVMCodepointIter *ci, MVMGrapheme32 g) {
+    if (g < 0) {
+        /* Get the synthetics info. */
+        MVMNFGSynthetic *synth = MVM_nfg_get_synthetic_info(tc, g);
+        /* Set up the iterator so in the next iteration we will start to
+        * hand back combiners. */
+        ci->synth_codes         = synth->combs;
+        ci->visited_synth_codes = 0;
+        ci->total_synth_codes   = synth->num_combs;
+
+        /* Return the base character of the grapheme. */
+        return synth->base;
+    }
+    else {
+        ci->synth_codes         = NULL;
+        ci->visited_synth_codes = 0;
+        ci->total_synth_codes   = 0;
+        return g;
+    }
+}
+MVM_STATIC_INLINE MVMCodepoint MVM_grapheme_ci_get_codepoint(MVMThreadContext *tc, MVMCodepointIter *ci) {
+    MVMCodepoint result;
+    result = ci->synth_codes[ci->visited_synth_codes];
+    ci->visited_synth_codes++;
+    if (ci->visited_synth_codes == ci->total_synth_codes)
+        ci->synth_codes = NULL;
+    return result;
+}
 
 /* Checks if there is more to read from a code point iterator; this is the
  * case if we're still walking through a synthetic or we have more things
@@ -178,6 +207,9 @@ MVM_STATIC_INLINE void MVM_string_ci_init(MVMThreadContext *tc, MVMCodepointIter
 MVM_STATIC_INLINE MVMint32 MVM_string_ci_has_more(MVMThreadContext *tc, MVMCodepointIter *ci) {
     return ci->synth_codes || MVM_string_gi_has_more(tc, &(ci->gi));
 }
+MVM_STATIC_INLINE MVMint32 MVM_grapheme_ci_has_more(MVMThreadContext *tc, MVMCodepointIter *ci) {
+    return ci->synth_codes ? 1 : 0;
+}
 
 /* Gets the next code point. */
 MVM_STATIC_INLINE MVMCodepoint MVM_string_ci_get_codepoint(MVMThreadContext *tc, MVMCodepointIter *ci) {