Refactor ALL the things!

src/parsers/xor.c

@@ -0,0 +1,44 @@
+#include "parser_internal.h"
+
+typedef struct {
+  const HParser *p1;
+  const HParser *p2;
+} HTwoParsers;
+
+
+static HParseResult* parse_xor(void *env, HParseState *state) {
+  HTwoParsers *parsers = (HTwoParsers*)env;
+  // cache the initial state of the input stream
+  HInputStream start_state = state->input_stream;
+  HParseResult *r1 = h_do_parse(parsers->p1, state);
+  HInputStream after_p1_state = state->input_stream;
+  // reset input stream, parse again
+  state->input_stream = start_state;
+  HParseResult *r2 = h_do_parse(parsers->p2, state);
+  if (NULL == r1) {
+    if (NULL != r2) {
+      return r2;
+    } else {
+      return NULL;
+    }
+  } else {
+    if (NULL == r2) {
+      state->input_stream = after_p1_state;
+      return r1;
+    } else {
+      return NULL;
+    }
+  }
+}
+
+static const HParserVtable xor_vt = {
+  .parse = parse_xor,
+};
+
+const HParser* h_xor(const HParser* p1, const HParser* p2) { 
+  HTwoParsers *env = g_new(HTwoParsers, 1);
+  env->p1 = p1; env->p2 = p2;
+  HParser *ret = g_new(HParser, 1);
+  ret->vtable = &xor_vt; ret->env = (void*)env;
+  return ret;
+}