src: refactor method parsing

Use a switch and a macro to branch parsing of HTTP methods. Easier to read and much shorter. In this commit, the order of branches dispatching is the same as in the original code, to ease review. Reordering branches by descending frequency will improve speed too. PR-URL: nodejs#273 Reviewed-By: Fedor Indutny <fedor@indutny.com>
bnoordhuis · Feb 27, 2016 · fd65b0f · fd65b0f
1 parent 678a9e2
commit fd65b0f
Showing 1 changed file with 31 additions and 80 deletions.
diff --git a/http_parser.c b/http_parser.c
@@ -1007,89 +1007,40 @@ size_t http_parser_execute (http_parser *parser,
           UPDATE_STATE(s_req_spaces_before_url);
         } else if (ch == matcher[parser->index]) {
           ; /* nada */
-        } else if (parser->method == HTTP_CONNECT) {
-          if (parser->index == 1 && ch == 'H') {
-            parser->method = HTTP_CHECKOUT;
-          } else if (parser->index == 2  && ch == 'P') {
-            parser->method = HTTP_COPY;
-          } else {
-            SET_ERRNO(HPE_INVALID_METHOD);
-            goto error;
-          }
-        } else if (parser->method == HTTP_MKCOL) {
-          if (parser->index == 1 && ch == 'O') {
-            parser->method = HTTP_MOVE;
-          } else if (parser->index == 1 && ch == 'E') {
-            parser->method = HTTP_MERGE;
-          } else if (parser->index == 1 && ch == '-') {
-            parser->method = HTTP_MSEARCH;
-          } else if (parser->index == 2 && ch == 'A') {
-            parser->method = HTTP_MKACTIVITY;
-          } else if (parser->index == 3 && ch == 'A') {
-            parser->method = HTTP_MKCALENDAR;
-          } else {
-            SET_ERRNO(HPE_INVALID_METHOD);
-            goto error;
-          }
-        } else if (parser->method == HTTP_SUBSCRIBE) {
-          if (parser->index == 1 && ch == 'E') {
-            parser->method = HTTP_SEARCH;
-          } else {
-            SET_ERRNO(HPE_INVALID_METHOD);
-            goto error;
-          }
-        } else if (parser->method == HTTP_REPORT) {
-            if (parser->index == 2 && ch == 'B') {
-              parser->method = HTTP_REBIND;
-            } else {
-              SET_ERRNO(HPE_INVALID_METHOD);
-              goto error;
-            }
-        } else if (parser->index == 1) {
-          if (parser->method == HTTP_POST) {
-            if (ch == 'R') {
-              parser->method = HTTP_PROPFIND; /* or HTTP_PROPPATCH */
-            } else if (ch == 'U') {
-              parser->method = HTTP_PUT; /* or HTTP_PURGE */
-            } else if (ch == 'A') {
-              parser->method = HTTP_PATCH;
-            } else {
-              SET_ERRNO(HPE_INVALID_METHOD);
-              goto error;
-            }
-          } else if (parser->method == HTTP_LOCK) {
-            if (ch == 'I') {
-              parser->method = HTTP_LINK;
-            } else {
-              SET_ERRNO(HPE_INVALID_METHOD);
-              goto error;
-            }
-          }
-        } else if (parser->index == 2) {
-          if (parser->method == HTTP_PUT) {
-            if (ch == 'R') {
-              parser->method = HTTP_PURGE;
-            } else {
-              SET_ERRNO(HPE_INVALID_METHOD);
-              goto error;
-            }
-          } else if (parser->method == HTTP_UNLOCK) {
-            if (ch == 'S') {
-              parser->method = HTTP_UNSUBSCRIBE;
-            } else if(ch == 'B') {
-              parser->method = HTTP_UNBIND;
-            } else {
+        } else if (IS_ALPHA(ch)) {
+
+          switch (parser->method << 16 | parser->index << 8 | ch) {
+#define XX(meth, pos, ch, new_meth) \
+            case (HTTP_##meth << 16 | pos << 8 | ch): \
+              parser->method = HTTP_##new_meth; break;
+
+            XX(POST,      1, 'U', PUT)
+            XX(POST,      1, 'A', PATCH)
+            XX(CONNECT,   1, 'H', CHECKOUT)
+            XX(CONNECT,   2, 'P', COPY)
+            XX(MKCOL,     1, 'O', MOVE)
+            XX(MKCOL,     1, 'E', MERGE)
+            XX(MKCOL,     2, 'A', MKACTIVITY)
+            XX(MKCOL,     3, 'A', MKCALENDAR)
+            XX(SUBSCRIBE, 1, 'E', SEARCH)
+            XX(REPORT,    2, 'B', REBIND)
+            XX(POST,      1, 'R', PROPFIND)
+            XX(PROPFIND,  4, 'P', PROPPATCH)
+            XX(PUT,       2, 'R', PURGE)
+            XX(LOCK,      1, 'I', LINK)
+            XX(UNLOCK,    2, 'S', UNSUBSCRIBE)
+            XX(UNLOCK,    2, 'B', UNBIND)
+            XX(UNLOCK,    3, 'I', UNLINK)
+#undef XX
+
+            default:
               SET_ERRNO(HPE_INVALID_METHOD);
               goto error;
-            }
-          } else {
-            SET_ERRNO(HPE_INVALID_METHOD);
-            goto error;
           }
-        } else if (parser->index == 4 && parser->method == HTTP_PROPFIND && ch == 'P') {
-          parser->method = HTTP_PROPPATCH;
-        } else if (parser->index == 3 && parser->method == HTTP_UNLOCK && ch == 'I') {
-          parser->method = HTTP_UNLINK;
+        } else if (ch == '-' &&
+                   parser->index == 1 &&
+                   parser->method == HTTP_MKCOL) {
+          parser->method = HTTP_MSEARCH;
         } else {
           SET_ERRNO(HPE_INVALID_METHOD);
           goto error;