// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import {constants} from './constants.js';
import {ParagraphUtils} from './paragraph_utils.js';
const RoleType = chrome.automation.RoleType;
/**
* Utilities for processing sentences within strings and node groups.
*/
export class SentenceUtils {
/**
* Gets the sentence start from the current position. When |direction| is set
* to forward, this function will incrementally go over each nodeGroupItem in
* |nodeGroup|, and try to find a sentence start index after the
* |startCharIndex|. When |direction| is set to backward, This function will
* search for the sentence start before the current position. The
* |startCharIndex| and the found sentence start index are relative to the
* text content of this node group.
* @param nodeGroup The node group this function
* will search.
* @param startCharIndex The char index that we start from. This
* index is relative to the text content of this node group and is
* exclusive: if a sentence start at 0 and we search with a 0
* |startCharIndex|, this function will return the next sentence start
* after 0 if we search forward.
* @param direction Direction to search for the next sentence
* start. |constants.Dir.BACKWARD| will search for the sentence start
* before the current position. |constants.Dir.FORWARD| will search for
* the sentence start after the current position.
* @return The next sentence start after |startCharIndex|, returns
* null if nothing found.
*/
static getSentenceStart(
nodeGroup: ParagraphUtils.NodeGroup, startCharIndex: number,
direction: constants.Dir): number|null {
if (!nodeGroup) {
return null;
}
if (nodeGroup.nodes.length === 0) {
return null;
}
if (direction === constants.Dir.FORWARD) {
for (let i = 0; i < nodeGroup.nodes.length; i++) {
const nodeGroupItem = nodeGroup.nodes[i];
const result = SentenceUtils.getSentenceStartInNodeGroupItem(
nodeGroupItem, startCharIndex, constants.Dir.FORWARD);
if (result !== null) {
return result;
}
}
} else if (direction === constants.Dir.BACKWARD) {
for (let i = nodeGroup.nodes.length - 1; i >= 0; i--) {
const nodeGroupItem = nodeGroup.nodes[i];
const result = SentenceUtils.getSentenceStartInNodeGroupItem(
nodeGroupItem, startCharIndex, constants.Dir.BACKWARD);
if (result !== null) {
return result;
}
}
}
return null;
}
/**
* Gets the sentence start before or after current position within the input
* |nodeGroupItem|.
* @param nodeGroupItem The node group item
* this function will search.
* @param startCharIndex The char index that we start from. This is
* relative to the text content of the node group.
* @param direction Direction to search for the next sentence
* start. |constants.Dir.BACKWARD| will search for the sentence start
* before the current position. |constants.Dir.FORWARD| will search for
* the sentence start after the current position.
* @return The next sentence start after |startCharIndex|, returns
* null if nothing found.
*/
static getSentenceStartInNodeGroupItem(
nodeGroupItem: ParagraphUtils.NodeGroupItem, startCharIndex: number,
direction: constants.Dir): number|null {
if (!nodeGroupItem) {
return null;
}
// Check if this nodeGroupItem has a non-empty static text node.
if (nodeGroupItem.node.role !== RoleType.STATIC_TEXT ||
nodeGroupItem.node.name!.length === 0) {
return null;
}
const staticTextStartChar = nodeGroupItem.startChar;
const staticTextNode = nodeGroupItem.node;
if (direction === constants.Dir.FORWARD) {
// If the corresponding char of |startCharIndex| is after this static text
// node, skip this text node.
if (startCharIndex >
staticTextStartChar + staticTextNode.name!.length - 1) {
return null;
}
// If the corresponding char of |startCharIndex| is within this static
// text node, we get its relative index in this static text. Otherwise,
// the start char is before this static text node, and any sentence start
// in this static text node is valid.
const searchIndexInStaticText =
Math.max(startCharIndex - staticTextStartChar, -1);
// Iterate over all sentenceStarts to find the one that is bigger than
// |searchIndexInStaticText|.
for (let i = 0; i < staticTextNode.sentenceStarts!.length; i++) {
if (staticTextNode.sentenceStarts![i] <= searchIndexInStaticText) {
continue;
}
return staticTextNode.sentenceStarts![i] + staticTextStartChar;
}
} else if (direction === constants.Dir.BACKWARD) {
// If the corresponding char of |startCharIndex| is before this static
// text node, skip this text node.
if (startCharIndex < staticTextStartChar) {
return null;
}
// If the corresponding char of |startCharIndex| is within this static
// text node, we get its relative index in this static text. Otherwise,
// the start char is after this static text node, and any sentence start
// in this static text node is valid.
const searchIndexInStaticText = Math.min(
startCharIndex - staticTextStartChar, staticTextNode.name!.length);
// Iterate over all sentenceStarts to find the one that is smaller than
// |searchIndexInStaticText|.
for (let i = staticTextNode.sentenceStarts!.length - 1; i >= 0; i--) {
if (staticTextNode.sentenceStarts![i] >= searchIndexInStaticText) {
continue;
}
return staticTextNode.sentenceStarts![i] + staticTextStartChar;
}
}
// We are off the edge of this static text node, return null.
return null;
}
/**
* Checks if the current position is a sentence start.
* @param nodeGroup The node group of the current
* position.
* @param currentCharIndex The char index of the current position.
* This is relative to the text content of the node group.
* @return Whether the current position is a start of a sentence.
*/
static isSentenceStart(
nodeGroup: ParagraphUtils.NodeGroup, currentCharIndex: number): boolean {
if (!nodeGroup) {
return false;
}
if (nodeGroup.nodes.length === 0) {
return false;
}
// Iterate over all the nodeGroupItems.
for (let i = 0; i < nodeGroup.nodes.length; i++) {
const nodeGroupItem = nodeGroup.nodes[i];
// Check if this nodeGroupItem has a non-empty static text node.
if (nodeGroupItem.node.role !== RoleType.STATIC_TEXT ||
nodeGroupItem.node.name!.length === 0) {
continue;
}
// Check if the corresponding char of |currentCharIndex| is inside this
// static text node.
const staticTextStartChar = nodeGroupItem.startChar;
const staticTextNode = nodeGroupItem.node;
if (currentCharIndex >
staticTextStartChar + staticTextNode.name!.length - 1 ||
currentCharIndex < staticTextStartChar) {
continue;
}
const searchIndexInStaticText = currentCharIndex - staticTextStartChar;
// Iterate over all sentenceStarts in the staticTextNode to see if we
// have |searchIndexInStaticText|.
for (let j = 0; j < staticTextNode.sentenceStarts!.length; j++) {
if (staticTextNode.sentenceStarts![j] === searchIndexInStaticText) {
return true;
}
}
}
// We did not find a sentence start equal to |currentCharIndex|.
return false;
}
}
Codebase Browser
chromium