tawasuyu/taffy

1
2class TrackSizingParser {
3  static INITIAL_CHAR_REGEX = /[a-z-A-Z0-9]/;
4  static TOKEN_CHAR_REGEX = /[-\.a-z-A-Z0-9%]/;
5
6  constructor(input, options = { allowFrUnits: true }) {
7    this.input = input;
8    this.index = 0;
9    this.options = options;
10  }
11
12  parseList() {
13    return this._parseItemList(' ', null);
14  }
15
16  parseSingleItem() {
17    return this.parseItem();
18  }
19
20  _parseItemList(separator, terminator = null) {
21    if (!separator) throw new Error('No terminator passed');
22    let tokenList = [];
23    // console.debug('Parse List', this.index, this.input.slice(this.index));
24
25    while (this.index < this.input.length) {
26      const char = this.input[this.index];
27      // console.debug(this.index, char);
28
29      // Skip whitespace
30      if (char === ' ') { this.index++; continue;}
31
32      if (TrackSizingParser.INITIAL_CHAR_REGEX.test(char)) {
33        const token = this._parseItem();
34        tokenList.push(token);
35
36        const nextChar = this.input[this.index];
37        if ((terminator && nextChar === terminator) || !terminator && !nextChar) {
38          return tokenList;
39        } else {
40          this.index++;
41          continue;
42        }
43      }
44
45      throw new Error (`Invalid start of token ${char}`);
46    }
47  }
48
49  _parseItem() {
50    let token = '';
51    // console.debug('Parse Item', this.index, this.input.slice(this.index));
52
53    while (this.index < this.input.length) {
54      const char = this.input[this.index];
55      // console.debug(this.index, char);
56
57      if (TrackSizingParser.TOKEN_CHAR_REGEX.test(char)) {
58        token += char;
59        this.index++;
60        continue;
61      }
62
63      if (char === '(') {
64        this.index++;
65        const args = this._parseItemList(',', ')');
66        this.index++;
67        return { kind: 'function', name: token, arguments: args };
68      }
69
70      return { kind: 'scalar', ...this._parseScalarItem(token) };
71    }
72    return { kind: 'scalar', ...this._parseScalarItem(token) };
73
74  }
75
76  _parseScalarItem(item) {
77    const res = parseRepetition(item) || parseDimension(item, { allowFrUnits: this.options.allowFrUnits });
78    if (!res) throw new Error(`Invalid scalar grid track sizing function ${item}`);
79    return res;
80  }
81
82}
83
84function parseRepetition(input) {
85  if (input === "auto-fill") return { unit: 'auto-fill' };
86  if (input === "auto-fit") return { unit: 'auto-fit' };
87  if (/^[0-9]*$/.test(input)) return { 'unit': 'integer', value: parseInt(input, 10) };
88  return undefined;
89}
90
91function parseDimension(input, options = { allowFrUnits: false }) {
92  if (options.allowFrUnits && input.endsWith('fr')) return { unit: 'fraction', value: parseFloat(input.replace('fr','')) };
93  if (input.endsWith('px')) return { unit: 'points',   value: parseFloat(input.replace('px','')) };
94  if (input.endsWith('%')) return { unit: 'percent',  value: parseFloat(input.replace('%','')) / 100 };
95  if (input === 'auto') return { unit: 'auto' };
96  if (input === 'min-content') return { unit: 'min-content' };
97  if (input === 'max-content') return { unit: 'max-content' };
98  return undefined;
99}
100
101function parseNumber(input) {
102  if (input === '' || isNaN(input)) return undefined;
103  return Number(input);
104}
105
106function parseEnum(input) {
107  if (input) return input;
108  return undefined;
109}
110
111function parseEdges(edges) {
112  const left = parseDimension(edges.left);
113  const right = parseDimension(edges.right);
114  const top = parseDimension(edges.top);
115  const bottom = parseDimension(edges.bottom);
116  
117  if (!left && !right && !top && !bottom) return undefined;
118  return { left, right, top, bottom };
119}
120
121function parseSize(size) {
122  const width = parseDimension(size.width);
123  const height = parseDimension(size.height);
124  
125  if (!width && !height) return undefined;
126  return { width, height };
127}
128
129function parseGaps(style) {
130  if (style.gap) {
131    const gaps = style.gap.trim().split(/\s+/).map(part => parseDimension(part));
132    return { row: gaps[0], column: gaps[1] ?? gaps[0] };
133  }
134  if (style.rowGap || style.columnGap) {
135    return { row: parseDimension(style.rowGap), column: parseDimension(style.columnGap) }
136  }
137  return undefined;
138}
139
140
141function parseGridTrackDefinitions(input) {
142  if (input === '') return undefined;
143  return new TrackSizingParser(input).parseList();
144}
145
146function parseGridAutoFlow(input) {
147  if (!/column/.test(input) && !/row/.test(input) && !/dense/.test(input)) return undefined;
148  const direction = /column/.test(input) ? 'column' : 'row';
149  const algorithm = /dense/.test(input) ? 'dense' : 'sparse';
150  return { direction, algorithm };
151}
152
153function parseGridPosition(input) {
154  if (input === 'auto') return { kind: 'auto' }
155  if (/^span +\d+$/.test(input)) return { kind: 'span', value: parseInt(input.replace(/[^\d]/g, ''), 10)}
156  if (/^-?\d+$/.test(input)) return { kind: 'line', value: parseInt(input, 10)}
157  return undefined;
158}
159
160function describeElement(e) {
161
162  return {
163    style: {
164      display: parseEnum(e.style.display),
165
166      position: parseEnum(e.style.position),
167      direction: parseEnum(e.style.direction),
168      flexDirection: parseEnum(e.style.flexDirection),
169
170      writingMode: parseEnum(e.style.writingMode),
171
172      flexWrap: parseEnum(e.style.flexWrap),
173      overflow: parseEnum(e.style.overflow),
174
175      alignItems: parseEnum(e.style.alignItems),
176      alignSelf: parseEnum(e.style.alignSelf),
177      justifyItems: parseEnum(e.style.justifyItems),
178      justifySelf: parseEnum(e.style.justifySelf),
179
180      alignContent: parseEnum(e.style.alignContent),
181      justifyContent: parseEnum(e.style.justifyContent),
182
183      flexGrow: parseNumber(e.style.flexGrow),
184      flexShrink: parseNumber(e.style.flexShrink),
185      flexBasis: parseDimension(e.style.flexBasis),
186
187      gridTemplateRows: parseGridTrackDefinitions(e.style.gridTemplateRows),
188      gridTemplateColumns: parseGridTrackDefinitions(e.style.gridTemplateColumns),
189      gridAutoRows: parseGridTrackDefinitions(e.style.gridAutoRows),
190      gridAutoColumns: parseGridTrackDefinitions(e.style.gridAutoColumns),
191      gridAutoFlow: parseGridAutoFlow(e.style.gridAutoFlow),
192
193      gridRowStart: parseGridPosition(e.style.gridRowStart),
194      gridRowEnd: parseGridPosition(e.style.gridRowEnd),
195      gridColumnStart: parseGridPosition(e.style.gridColumnStart),
196      gridColumnEnd: parseGridPosition(e.style.gridColumnEnd),
197
198      gap: parseGaps(e.style),
199
200      size: parseSize({width: e.style.width, height: e.style.height}),
201      minSize: parseSize({width: e.style.minWidth, height: e.style.minHeight}),
202      maxSize: parseSize({width: e.style.maxWidth, height: e.style.maxHeight}),
203
204      margin: parseEdges({
205        left: e.style.marginLeft,
206        right: e.style.marginRight,
207        top: e.style.marginTop,
208        bottom: e.style.marginBottom,
209      }),
210
211      padding: parseEdges({
212        left: e.style.paddingLeft,
213        right: e.style.paddingRight,
214        top: e.style.paddingTop,
215        bottom: e.style.paddingBottom,
216      }),
217
218      border: parseEdges({
219        left: e.style.borderLeftWidth,
220        right: e.style.borderRightWidth,
221        top: e.style.borderTopWidth,
222        bottom: e.style.borderBottomWidth,
223      }),
224
225      inset: parseEdges({
226        left: e.style.left,
227        right: e.style.right,
228        top: e.style.top,
229        bottom: e.style.bottom,
230      }),
231    },
232
233    // The textContent is used for generating intrinsic sizing measure funcs
234    // So we're only interested in the text content of leaf nodes
235    textContent: e.childElementCount === 0 && e.textContent.length && e.textContent !== "\n" ? e.textContent : undefined,
236
237    layout: {
238      width: e.offsetWidth,
239      height: e.offsetHeight,
240      x: e.offsetLeft + e.parentNode.clientLeft,
241      y: e.offsetTop + e.parentNode.clientTop,
242    },
243
244    children: Array.from(e.children).map(c => describeElement(c)),
245  }
246}
247
248// Useful when developing this script. Logs the parsed style to the console when any test fixture is opened in a browser.
249window.onload = function () {
250  try {
251    console.log(describeElement(document.getElementById('test-root')));
252  } catch (e) {
253    console.error(e);
254  }
255}