Export push processor & method for converting matrix glob to regexp (#4763)

* Export push processor method for converting matrix glob to regexp

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Export pushProcessor from MatrixClient

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Add capturing group around pattern match

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Improve comment

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

Author: t3chguy

src/client.ts

@@ -1234,7 +1234,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
     public canSupport = new Map<Feature, ServerSupport>();
 
     // The pushprocessor caches useful things, so keep one and re-use it
-    protected pushProcessor = new PushProcessor(this);
+    public readonly pushProcessor = new PushProcessor(this);
 
     // Promise to a response of the server's /versions response
     // TODO: This should expire: https://github.com/matrix-org/matrix-js-sdk/issues/1020

src/pushprocessor.ts

@@ -308,6 +308,26 @@ export class PushProcessor {
         return newRules;
     }
 
+    /**
+     * Create a RegExp object for the given glob pattern with a single capture group around the pattern itself, caching the result.
+     * No cache invalidation is present currently,
+     * as this will be inherently bounded to the size of the user's own push rules.
+     * @param pattern - the glob pattern to convert to a RegExp
+     * @param alignToWordBoundary - whether to align the pattern to word boundaries, as specified for `content.body` matches
+     * @param flags - the flags to pass to the RegExp constructor, defaults to case-insensitive
+     */
+    public static getPushRuleGlobRegex(pattern: string, alignToWordBoundary = false, flags = "i"): RegExp {
+        const [prefix, suffix] = alignToWordBoundary ? ["(^|\\W)", "(\\W|$)"] : ["^", "$"];
+
+        if (!PushProcessor.cachedGlobToRegex[pattern]) {
+            PushProcessor.cachedGlobToRegex[pattern] = new RegExp(
+                prefix + "(" + globToRegexp(pattern) + ")" + suffix,
+                flags,
+            );
+        }
+        return PushProcessor.cachedGlobToRegex[pattern];
+    }
+
     /**
      * Pre-caches the parsed keys for push rules and cleans out any obsolete cache
      * entries. Should be called after push rules are updated.
@@ -567,11 +587,9 @@ export class PushProcessor {
             return false;
         }
 
-        const regex =
-            cond.key === "content.body"
-                ? this.createCachedRegex("(^|\\W)", cond.pattern, "(\\W|$)")
-                : this.createCachedRegex("^", cond.pattern, "$");
-
+        // Align to word boundary on `content.body` matches, whole string otherwise
+        // https://spec.matrix.org/v1.13/client-server-api/#conditions-1
+        const regex = PushProcessor.getPushRuleGlobRegex(cond.pattern, cond.key === "content.body");
         return !!val.match(regex);
     }
 
@@ -621,17 +639,6 @@ export class PushProcessor {
         );
     }
 
-    private createCachedRegex(prefix: string, glob: string, suffix: string): RegExp {
-        if (PushProcessor.cachedGlobToRegex[glob]) {
-            return PushProcessor.cachedGlobToRegex[glob];
-        }
-        PushProcessor.cachedGlobToRegex[glob] = new RegExp(
-            prefix + globToRegexp(glob) + suffix,
-            "i", // Case insensitive
-        );
-        return PushProcessor.cachedGlobToRegex[glob];
-    }
-
     /**
      * Parse the key into the separate fields to search by splitting on
      * unescaped ".", and then removing any escape characters.