Fix hint bug.

In hinting.ts, pipe() and pipe_elements() assumed that the resolve
function they passed to hintPage() would always be called, which wasn't
always the case (e.g. when a users goes into hint mode but presses
`<Esc>`).

This caused unresolved promises to linger in the tab. When the tab was
closed, an error was thrown about the message manager being
disconnected. This was caught by Tridactyl and displayed in the command
line.

We're fixing this bug by passing no-op functions as onSelect to
hintPage() and explicitly passing the resolve function. The resolve
function is then saved in HintState and called when destroying
HintState.

We parametrize reset() in order to be able to distinguish between resets
caused by a hint being selected and by the user pressing `<Esc>`. This
is necessary because we need to know when the function should resolve
the last focused hint and when it shouldn't.

We then add a bunch of null handling in excmds.ts:hint() in order to
make sure not to introduce other bugs.

This fixes https://github.com/cmcaine/tridactyl/issues/855.

src/excmds.ts

@@ -2903,7 +2903,9 @@ export async function hint(option?: string, selectors?: string, ...rest: string[
 
     // Open in background
     if (option === "-b") {
-        let [link, hintCount] = await hinting.pipe(DOM.HINTTAGS_selectors)
+        let result = await hinting.pipe(DOM.HINTTAGS_selectors)
+        if (result === null) return null
+        let [link, hintCount] = result
         link.focus()
         if (link.href) {
             let containerId = await activeTabContainerId()
@@ -2927,17 +2929,22 @@ export async function hint(option?: string, selectors?: string, ...rest: string[
 
     // Yank link
     else if (option === "-y") {
-        run_exstr("yank " + (await hinting.pipe(DOM.HINTTAGS_selectors))[0]["href"])
+        let result = await hinting.pipe(DOM.HINTTAGS_selectors)
+        if (result === null) return null
+        run_exstr("yank " + result[0]["href"])
     }
 
     // Yank text content
     else if (option === "-p") {
-        run_exstr("yank " + (await hinting.pipe_elements(DOM.elementsWithText()))["textContent"])
+        let result = await hinting.pipe_elements(DOM.elementsWithText())
+        if (result === null) return null
+        run_exstr("yank " + result["textContent"])
     }
 
     // Yank link alt text
     else if (option === "-P") {
         let link = await hinting.pipe_elements(DOM.getElemsBySelector("[title], [alt]", [DOM.isVisible]))
+        if (link === null) return link
         run_exstr("yank " + (link.title ? link.title : link.alt))
     }
 
@@ -2945,15 +2952,28 @@ export async function hint(option?: string, selectors?: string, ...rest: string[
     else if (option === "-#") {
         let anchorUrl = new URL(window.location.href)
         let link = await hinting.pipe_elements(DOM.anchors())
+        if (link === null) return null
         anchorUrl.hash = link.id || link.name
         run_exstr("yank " + anchorUrl.href)
-    } else if (option === "-c") DOM.simulateClick((await hinting.pipe(selectors))[0])
+    } else if (option === "-c") {
+        let result = await hinting.pipe(selectors)
+        if (result === null) return null
+        DOM.simulateClick(result[0])
+    }
     // Deprecated: hint exstr
-    else if (option === "-W") run_exstr(selectors + " " + rest.join(" ") + " " + (await hinting.pipe(DOM.HINTTAGS_selectors))[0])
-    else if (option === "-pipe") return (await hinting.pipe(selectors))[0][rest.join(" ")]
-    else if (option === "-br") {
+    else if (option === "-W") {
+        let result = await hinting.pipe(DOM.HINTTAGS_selectors)
+        if (result === null) return null
+        run_exstr(selectors + " " + rest.join(" ") + " " + result[0])
+    } else if (option === "-pipe") {
+        let result = await hinting.pipe(selectors)
+        if (result === null) return null
+        return result[0][rest.join(" ")]
+    } else if (option === "-br") {
         while (true) {
-            let [_, hintCount] = await hint("-b")
+            let result = await hint("-b")
+            if (result === null) return null
+            let [_, hintCount] = result
             if (hintCount < 2) break
         }
     }
@@ -2970,7 +2990,11 @@ export async function hint(option?: string, selectors?: string, ...rest: string[
     else if (option === "-r") hinting.hintRead()
     else if (option === "-w") hinting.hintPageWindow()
     else if (option === "-wp") hinting.hintPageWindowPrivate()
-    else DOM.simulateClick((await hinting.pipe(DOM.HINTTAGS_selectors))[0])
+    else {
+        let result = await hinting.pipe(DOM.HINTTAGS_selectors)
+        if (result === null) return null
+        DOM.simulateClick(result[0])
+    }
 }
 
 // how 2 crash pc

src/hinting.ts

@@ -36,11 +36,11 @@ class HintState {
     public filter = ""
     public hintchars = ""
 
-    constructor(public filterFunc: HintFilter) {
+    constructor(public filterFunc: HintFilter, public resolve: (Hint) => void) {
         this.hintHost.classList.add("TridactylHintHost", "cleanslate")
     }
 
-    destructor() {
+    destructor(abort) {
         // Undo any alterations of the hinted elements
         for (const hint of this.hints) {
             hint.hidden = true
@@ -48,6 +48,9 @@ class HintState {
 
         // Remove all hints from the DOM.
         this.hintHost.remove()
+
+        if (abort) this.resolve(null)
+        else this.resolve(this.focusedHint)
     }
 }
 
@@ -57,11 +60,13 @@ let modeState: HintState = undefined
 export function hintPage(
     hintableElements: Element[],
     onSelect: HintSelectedCallback,
-    buildHints: HintBuilder = defaultHintBuilder(),
-    filterHints: HintFilter = defaultHintFilter(),
+    resolve = () => {},
 ) {
+    let buildHints: HintBuilder = defaultHintBuilder()
+    let filterHints: HintFilter = defaultHintFilter()
     state.mode = "hint"
-    modeState = new HintState(filterHints)
+    modeState = new HintState(filterHints, resolve)
+
     buildHints(hintableElements, onSelect)
 
     if (modeState.hints.length) {
@@ -421,9 +426,12 @@ function filterHintsVimperator(fstr, reflow = false) {
     }
 }
 
-/** Remove all hints, reset STATE. */
-function reset() {
-    modeState.destructor()
+/** Remove all hints, reset STATE.
+ *  If abort is true, we're resetting because the user pressed escape.
+ *  If it is false, we're resetting because the user selected a hint.
+ **/
+function reset(abort = false) {
+    modeState.destructor(abort)
     modeState = undefined
     state.mode = "normal"
 }
@@ -509,9 +517,10 @@ export async function pipe(
 ): Promise<[any, number]> {
     let hintCount = hintables(selectors, true).length
     let hint = await new Promise(resolve => {
-        hintPage(hintables(selectors, true), resolve)
+        hintPage(hintables(selectors, true), () => {}, resolve)
     })
-    return [(hint as any).target, hintCount]
+    if (hint) return [(hint as any).target, hintCount]
+    else return null
     // Promise takes function which it calls immediately with another function
     // as its argument. When this second function is called, it gives its
     // argument to the promise as its value
@@ -519,9 +528,10 @@ export async function pipe(
 
 export async function pipe_elements(elements: any = DOM.elementsWithText) {
     let hint = await new Promise(resolve => {
-        hintPage(elements, resolve)
+        hintPage(elements, () => {}, resolve)
     })
-    return (hint as any).target
+    if (hint) return (hint as any).target
+    else return null
 }
 
 /** Hint images, opening in the same tab, or in a background tab

src/hinting_background.ts

@@ -8,8 +8,9 @@ async function selectFocusedHint() {
     return await messageActiveTab("hinting_content", "selectFocusedHint")
 }
 
-async function reset() {
-    return await messageActiveTab("hinting_content", "reset")
+/* abort = true means that we're resetting because the user pressed escape */
+async function reset(abort = false) {
+    return await messageActiveTab("hinting_content", "reset", [abort])
 }
 
 /** Type for "hint save" actions:
@@ -30,7 +31,7 @@ import { MsgSafeKeyboardEvent } from "./msgsafe"
 export function parser(keys: MsgSafeKeyboardEvent[]) {
     const key = keys[0].key
     if (key === "Escape") {
-        reset()
+        reset(true)
     } else if (["Enter", " "].includes(key)) {
         selectFocusedHint()
     } else {