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4a288a7 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 | // @flow
import type {SymbolFeature} from '../data/bucket/symbol_bucket';
export default function (features: Array<SymbolFeature>): Array<SymbolFeature> {
const leftIndex: {[_: string]: number} = {};
const rightIndex: {[_: string]: number} = {};
const mergedFeatures = [];
let mergedIndex = 0;
function add(k) {
mergedFeatures.push(features[k]);
mergedIndex++;
}
function mergeFromRight(leftKey: string, rightKey: string, geom) {
const i = rightIndex[leftKey];
delete rightIndex[leftKey];
rightIndex[rightKey] = i;
mergedFeatures[i].geometry[0].pop();
mergedFeatures[i].geometry[0] = mergedFeatures[i].geometry[0].concat(geom[0]);
return i;
}
function mergeFromLeft(leftKey: string, rightKey: string, geom) {
const i = leftIndex[rightKey];
delete leftIndex[rightKey];
leftIndex[leftKey] = i;
mergedFeatures[i].geometry[0].shift();
mergedFeatures[i].geometry[0] = geom[0].concat(mergedFeatures[i].geometry[0]);
return i;
}
function getKey(text, geom, onRight) {
const point = onRight ? geom[0][geom[0].length - 1] : geom[0][0];
return `${text}:${point.x}:${point.y}`;
}
for (let k = 0; k < features.length; k++) {
const feature = features[k];
const geom = feature.geometry;
const text = feature.text ? feature.text.toString() : null;
if (!text) {
add(k);
continue;
}
const leftKey = getKey(text, geom),
rightKey = getKey(text, geom, true);
if ((leftKey in rightIndex) && (rightKey in leftIndex) && (rightIndex[leftKey] !== leftIndex[rightKey])) {
// found lines with the same text adjacent to both ends of the current line, merge all three
const j = mergeFromLeft(leftKey, rightKey, geom);
const i = mergeFromRight(leftKey, rightKey, mergedFeatures[j].geometry);
delete leftIndex[leftKey];
delete rightIndex[rightKey];
rightIndex[getKey(text, mergedFeatures[i].geometry, true)] = i;
mergedFeatures[j].geometry = (null: any);
} else if (leftKey in rightIndex) {
// found mergeable line adjacent to the start of the current line, merge
mergeFromRight(leftKey, rightKey, geom);
} else if (rightKey in leftIndex) {
// found mergeable line adjacent to the end of the current line, merge
mergeFromLeft(leftKey, rightKey, geom);
} else {
// no adjacent lines, add as a new item
add(k);
leftIndex[leftKey] = mergedIndex - 1;
rightIndex[rightKey] = mergedIndex - 1;
}
}
return mergedFeatures.filter((f) => f.geometry);
}
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