feat(fsm): update str() to NOT collect input by default (match only)

thi-ng · Nov 3, 2019 · 6105ea7 · 6105ea7
1 parent ccc9d40
commit 6105ea7
Showing 1 changed file with 37 additions and 12 deletions.
diff --git a/packages/fsm/src/str.ts b/packages/fsm/src/str.ts
@@ -1,24 +1,49 @@
-import { LitCallback, Match, Matcher, RES_PARTIAL } from "./api";
+import {
+    LitCallback,
+    Match,
+    Matcher,
+    RES_PARTIAL
+} from "./api";
 import { result } from "./result";
 
 /**
  * String-only version of `seq()`. Returns `Match.FULL` once the entire
- * given string could be matched.
+ * given string could be matched. Unless `collect` is true (default:
+ * false), only matches given string and does not collect input.
+ * Therefore then also only passes an empty string to `fail` callback.
+ * If `collect` is true, the failed callback will be called with the
+ * collected input.
  *
  * @param str
  * @param success
  * @param fail
+ * @param collect
  */
 export const str = <C, R>(
     str: string,
     success?: LitCallback<string, C, R>,
-    fail?: LitCallback<string, C, R>
-): Matcher<string, C, R> => () => {
-    let buf = "";
-    return (ctx, x) =>
-        (buf += x) === str
-            ? result(success && success(ctx, buf))
-            : str.indexOf(buf) === 0
-                ? RES_PARTIAL
-                : result(fail && fail(ctx, buf), Match.FAIL);
-};
+    fail?: LitCallback<string, C, R>,
+    collect = false
+): Matcher<string, C, R> =>
+    collect
+        ? () => {
+              let buf = "";
+              return (ctx, x) =>
+                  (buf += x) === str
+                      ? result(success && success(ctx, buf))
+                      : str.indexOf(buf) === 0
+                      ? RES_PARTIAL
+                      : result(fail && fail(ctx, buf), Match.FAIL);
+          }
+        : () => {
+              let matched = 0;
+              let i = 0;
+              return (ctx, x) => {
+                  str.charAt(i++) === x && matched++;
+                  return matched === str.length
+                      ? result(success && success(ctx, str))
+                      : matched === i
+                      ? RES_PARTIAL
+                      : result(fail && fail(ctx, ""), Match.FAIL);
+              };
+          };