Engine

Reading obfuscated objects

Some patches hold an object and need a value from it that sits several renamed classes deep: the video URL of a feed post is post.attributes.videos[0].getUrl(), with every class on the way obfuscated. A binding describes that path once, structurally; any patch then applies it to a value inside a code block and gets the null-checked chain emitted.

val post = bind("post") {
    fromField("feedPostField") {
        owner(onPostClicked.owner)
        nearestObjectReadBeforeString("post_clicked")
    }
    string("videoUrl") {
        member("attributes")
        listGetter("videos") {
            rankBy("callers followed by cast") { callSitesFollowedByCast(VIDEO) }
        }
        first()
        cast(VIDEO)
        callInterface(VIDEO, "getUrl", "()Ljava/lang/String;")
    }
}

onPostClicked.before {
    call(Ext.onClick, post.member("videoUrl", thisObject.field(post.sourceField)))
}

PostRefs.videoUrl.implement { returnValue(post.member("videoUrl", param(0))) }

The source (fromField, fromMethod, fromClass) finds the root class. Members (string, objectValue, intValue, context, bind) are named paths of steps: field reads by type or by locator, calls, casts, list element, another member as a prefix. The label names the binding in reports and logs. raw { } is the path from the input value to the root itself.

binding.of(value) applies the raw path; binding.member(name, value) a member. The input must be assignable to the root type; an Object-typed input is cast implicitly. A null anywhere on the path makes the result null or zero. Steps and sources are listed in the reference.

Warning

A binding knows the class, not where the object is held. The patch still reads it: thisObject.field(post.sourceField). A member that reaches a null yields null rather than crashing, so handle it with whenNotNull.

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