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DOMTextScanner updates (#2146)

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* JSDoc updates

* Move function

* Simplify

* Refactor return type

* Refactor getElementSeekInfo return type
This commit is contained in:
toasted-nutbread 2022-05-18 21:43:19 -04:00 committed by GitHub
parent a33a00f5ae
commit 6e239638bb
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1 changed files with 69 additions and 73 deletions
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142
ext/js/dom/dom-text-scanner.js
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@ -44,7 +44,7 @@ class DOMTextScanner {
/**
* Gets the current node being scanned.
* @returns A DOM Node.
* @type {Node}
*/
get node() {
return this._node;
@ -53,7 +53,7 @@ class DOMTextScanner {
/**
* Gets the current offset corresponding to the node being scanned.
* This value is only applicable for text nodes.
* @returns An integer.
* @type {number}
*/
get offset() {
return this._offset;
@ -62,7 +62,7 @@ class DOMTextScanner {
/**
* Gets the remaining number of characters that weren't scanned in the last seek() call.
* This value is usually 0 unless the end of the document was reached.
* @returns An integer.
* @type {number}
*/
get remainder() {
return this._remainder;
@ -70,7 +70,7 @@ class DOMTextScanner {
/**
* Gets the accumulated content string resulting from calls to seek().
* @returns A string.
* @type {string}
*/
get content() {
return this._content;
@ -78,11 +78,11 @@ class DOMTextScanner {
/**
* Seeks a given length in the document and accumulates the text content.
* @param length A positive or negative integer corresponding to how many characters
* @param {number} length A positive or negative integer corresponding to how many characters
* should be added to content. Content is only added to the accumulation string,
* never removed, so mixing seek calls with differently signed length values
* may give unexpected results.
* @returns this
* @returns {DOMTextScanner} this
*/
seek(length) {
const forward = (length >= 0);
@ -114,7 +114,7 @@ class DOMTextScanner {
} else if (nodeType === ELEMENT_NODE) {
lastNode = node;
this._offset = 0;
[enterable, newlines] = DOMTextScanner.getElementSeekInfo(node);
({enterable, newlines} = DOMTextScanner.getElementSeekInfo(node));
if (newlines > this._newlines && generateLayoutContent) {
this._newlines = newlines;
}
@ -125,7 +125,7 @@ class DOMTextScanner {
for (const exitedNode of exitedNodes) {
if (exitedNode.nodeType !== ELEMENT_NODE) { continue; }
newlines = DOMTextScanner.getElementSeekInfo(exitedNode)[1];
({newlines} = DOMTextScanner.getElementSeekInfo(exitedNode));
if (newlines > this._newlines && generateLayoutContent) {
this._newlines = newlines;
}
@ -144,18 +144,14 @@ class DOMTextScanner {
/**
* Seeks forward in a text node.
* @param textNode The text node to use.
* @param resetOffset Whether or not the text offset should be reset.
* @returns true if scanning should continue, or false if the scan length has been reached.
* @param {Text} textNode The text node to use.
* @param {boolean} resetOffset Whether or not the text offset should be reset.
* @returns {boolean} `true` if scanning should continue, or `false` if the scan length has been reached.
*/
_seekTextNodeForward(textNode, resetOffset) {
const nodeValue = textNode.nodeValue;
const nodeValueLength = nodeValue.length;
const [preserveNewlines, preserveWhitespace] = (
this._forcePreserveWhitespace ?
[true, true] :
DOMTextScanner.getWhitespaceSettings(textNode)
);
const {preserveNewlines, preserveWhitespace} = this._getWhitespaceSettings(textNode);
let lineHasWhitespace = this._lineHasWhitespace;
let lineHasContent = this._lineHasContent;
@ -234,18 +230,14 @@ class DOMTextScanner {
* - offset is decremented before getting the character.
* - offset is reverted by incrementing instead of decrementing.
* - content string is prepended instead of appended.
* @param textNode The text node to use.
* @param resetOffset Whether or not the text offset should be reset.
* @returns true if scanning should continue, or false if the scan length has been reached.
* @param {Text} textNode The text node to use.
* @param {boolean} resetOffset Whether or not the text offset should be reset.
* @returns {boolean} `true` if scanning should continue, or `false` if the scan length has been reached.
*/
_seekTextNodeBackward(textNode, resetOffset) {
const nodeValue = textNode.nodeValue;
const nodeValueLength = nodeValue.length;
const [preserveNewlines, preserveWhitespace] = (
this._forcePreserveWhitespace ?
[true, true] :
DOMTextScanner.getWhitespaceSettings(textNode)
);
const {preserveNewlines, preserveWhitespace} = this._getWhitespaceSettings(textNode);
let lineHasWhitespace = this._lineHasWhitespace;
let lineHasContent = this._lineHasContent;
@ -315,15 +307,41 @@ class DOMTextScanner {
return (remainder > 0);
}
/**
* Gets information about how whitespace characters are treated.
* @param {Text} textNode The text node to check.
* @returns {{preserveNewlines: boolean, preserveWhitespace: boolean}} Information about the whitespace.
* The value of `preserveNewlines` indicates whether or not newline characters are treated as line breaks.
* The value of `preserveWhitespace` indicates whether or not sequences of whitespace characters are collapsed.
*/
_getWhitespaceSettings(textNode) {
if (this._forcePreserveWhitespace) {
return {preserveNewlines: true, preserveWhitespace: true};
}
const element = DOMTextScanner.getParentElement(textNode);
if (element !== null) {
const style = window.getComputedStyle(element);
switch (style.whiteSpace) {
case 'pre':
case 'pre-wrap':
case 'break-spaces':
return {preserveNewlines: true, preserveWhitespace: true};
case 'pre-line':
return {preserveNewlines: true, preserveWhitespace: false};
}
}
return {preserveNewlines: false, preserveWhitespace: false};
}
// Static helpers
/**
* Gets the next node in the document for a specified scanning direction.
* @param node The current DOM Node.
* @param forward Whether to scan forward in the document or backward.
* @param visitChildren Whether the children of the current node should be visited.
* @param exitedNodes An array which stores nodes which were exited.
* @returns The next node in the document, or null if there is no next node.
* @param {Node} node The current DOM Node.
* @param {boolean} forward Whether to scan forward in the document or backward.
* @param {boolean} visitChildren Whether the children of the current node should be visited.
* @param {Node[]} exitedNodes An array which stores nodes which were exited.
* @returns {?Node} The next node in the document, or `null` if there is no next node.
*/
static getNextNode(node, forward, visitChildren, exitedNodes) {
let next = visitChildren ? (forward ? node.firstChild : node.lastChild) : null;
@ -345,8 +363,8 @@ class DOMTextScanner {
/**
* Gets the parent element of a given Node.
* @param node The node to check.
* @returns The parent element if one exists, otherwise null.
* @param {Node} node The node to check.
* @returns {?Node} The parent element if one exists, otherwise `null`.
*/
static getParentElement(node) {
while (node !== null && node.nodeType !== Node.ELEMENT_NODE) {
@ -359,8 +377,8 @@ class DOMTextScanner {
* Gets the parent <ruby> element of a given node, if one exists. For efficiency purposes,
* this only checks the immediate parent elements and does not check all ancestors, so
* there are cases where the node may be in a ruby element but it is not returned.
* @param node The node to check.
* @returns A <ruby> node if the input node is contained in one, otherwise null.
* @param {Node} node The node to check.
* @returns {?HTMLElement} A <ruby> node if the input node is contained in one, otherwise `null`.
*/
static getParentRubyElement(node) {
node = DOMTextScanner.getParentElement(node);
@ -374,9 +392,10 @@ class DOMTextScanner {
}
/**
* @returns [enterable: boolean, newlines: integer]
* The enterable value indicates whether the content of this node should be entered.
* The newlines value corresponds to the number of newline characters that should be added.
* Gets seek information about an element.
* @returns {{enterable: boolean, newlines: number}} The seek information.
* The `enterable` value indicates whether the content of this node should be entered.
* The `newlines` value corresponds to the number of newline characters that should be added.
* 1 newline corresponds to a simple new line in the layout.
* 2 newlines corresponds to a significant visual distinction since the previous content.
*/
@ -387,9 +406,9 @@ class DOMTextScanner {
case 'RT':
case 'SCRIPT':
case 'STYLE':
return [false, 0];
return {enterable: false, newlines: 0};
case 'BR':
return [false, 1];
return {enterable: false, newlines: 1};
case 'TEXTAREA':
case 'INPUT':
case 'BUTTON':
@ -418,36 +437,13 @@ class DOMTextScanner {
}
}
return [enterable, newlines];
}
/**
* Gets information about how whitespace characters are treated.
* @param textNode The Text node to check.
* @returns [preserveNewlines: boolean, preserveWhitespace: boolean]
* The value of preserveNewlines indicates whether or not newline characters are treated as line breaks.
* The value of preserveWhitespace indicates whether or not sequences of whitespace characters are collapsed.
*/
static getWhitespaceSettings(textNode) {
const element = DOMTextScanner.getParentElement(textNode);
if (element !== null) {
const style = window.getComputedStyle(element);
switch (style.whiteSpace) {
case 'pre':
case 'pre-wrap':
case 'break-spaces':
return [true, true];
case 'pre-line':
return [true, false];
}
}
return [false, false];
return {enterable, newlines};
}
/**
* Gets attributes for the specified character.
* @param character A string containing a single character.
* @returns An integer representing the attributes of the character.
* @param {string} character A string containing a single character.
* @returns {number} An integer representing the attributes of the character.
* 0: Character should be ignored.
* 1: Character is collapsible whitespace.
* 2: Character should be added to the content.
@ -472,9 +468,9 @@ class DOMTextScanner {
/**
* Checks whether a given style is visible or not.
* This function does not check style.display === 'none'.
* @param style An object implementing the CSSStyleDeclaration interface.
* @returns true if the style should result in an element being visible, otherwise false.
* This function does not check `style.display === 'none'`.
* @param {CSSStyleDeclaration} style An object implementing the CSSStyleDeclaration interface.
* @returns {boolean} `true` if the style should result in an element being visible, otherwise `false`.
*/
static isStyleVisible(style) {
return !(
@ -493,8 +489,8 @@ class DOMTextScanner {
/**
* Checks whether a given style is selectable or not.
* @param style An object implementing the CSSStyleDeclaration interface.
* @returns true if the style is selectable, otherwise false.
* @param {CSSStyleDeclaration} style An object implementing the CSSStyleDeclaration interface.
* @returns {boolean} `true` if the style is selectable, otherwise `false`.
*/
static isStyleSelectable(style) {
return !(
@ -507,8 +503,8 @@ class DOMTextScanner {
/**
* Checks whether a CSS color is transparent or not.
* @param cssColor A CSS color string, expected to be encoded in rgb(a) form.
* @returns true if the color is transparent, otherwise false.
* @param {string} cssColor A CSS color string, expected to be encoded in rgb(a) form.
* @returns {false} `true` if the color is transparent, otherwise `false`.
*/
static isCSSColorTransparent(cssColor) {
return (
@ -520,8 +516,8 @@ class DOMTextScanner {
/**
* Checks whether a CSS display value will cause a layout change for text.
* @param cssDisplay A CSS string corresponding to the value of the display property.
* @returns true if the layout is changed by this value, otherwise false.
* @param {string} cssDisplay A CSS string corresponding to the value of the display property.
* @returns {boolean} `true` if the layout is changed by this value, otherwise `false`.
*/
static doesCSSDisplayChangeLayout(cssDisplay) {
let pos = cssDisplay.indexOf(' ');