« get me outta code hell

ansi.js « util - tui-lib - Pure Node.js library for making visual command-line programs (ala vim, ncdu)
about summary refs log tree commit diff
path: root/util/ansi.js
blob: 997e82411ba4cd9ef3330e1e123dde89f7125538 (plain)
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
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
import wcwidth from 'wcwidth'

function isDigit(char) {
  return '0123456789'.indexOf(char) >= 0
}

export const ESC = '\x1b'

// Attributes
export const A_RESET =   0
export const A_BRIGHT =  1
export const A_DIM =     2
export const A_INVERT =  7

// Colors
export const C_BLACK =    30
export const C_RED =      31
export const C_GREEN =    32
export const C_YELLOW =   33
export const C_BLUE =     34
export const C_MAGENTA =  35
export const C_CYAN =     36
export const C_WHITE =    37
export const C_RESET =    39

export function clearScreen() {
  // Clears the screen, removing any characters displayed, and resets the
  // cursor position.

  return `${ESC}[2J`
}

export function moveCursorRaw(line, col) {
  // Moves the cursor to the given line and column on the screen.
  // Returns the pure ANSI code, with no modification to line or col.

  return `${ESC}[${line};${col}H`
}

export function moveCursor(line, col) {
  // Moves the cursor to the given line and column on the screen.
  // Note that since in JavaScript indexes start at 0, but in ANSI codes
  // the top left of the screen is (1, 1), this function adjusts the
  // arguments to act as if the top left of the screen is (0, 0).

  return `${ESC}[${line + 1};${col + 1}H`
}

export function cleanCursor() {
  // A combination of codes that generally cleans up the cursor.

  return resetAttributes() +
    stopTrackingMouse() +
    showCursor()
}

export function hideCursor() {
  // Makes the cursor invisible.

  return `${ESC}[?25l`
}

export function showCursor() {
  // Makes the cursor visible.

  return `${ESC}[?25h`
}

export function resetAttributes() {
  // Resets all attributes, including text decorations, foreground and
  // background color.

  return `${ESC}[0m`
}

export function setAttributes(attrs) {
  // Set some raw attributes. See the attributes section of the ansi.js
  // source code for attributes that can be used with this; A_RESET resets
  // all attributes.

  return `${ESC}[${attrs.join(';')}m`
}

export function setForeground(color) {
  // Sets the foreground color to print text with. See C_(COLOR) for colors
  // that can be used with this; C_RESET resets the foreground.
  //
  // If null or undefined is passed, this function will return a blank
  // string (no ANSI escape codes).

  if (typeof color === 'undefined' || color === null) {
    return ''
  }

  return setAttributes([color])
}

export function setBackground(color) {
  // Sets the background color to print text with. Accepts the same arguments
  // as setForeground (C_(COLOR), C_RESET, etc).
  //
  // Note that attributes such as A_BRIGHT and A_DIM apply apply to only the
  // foreground, not the background. To set a bright or dim background, you
  // can set the appropriate color as the foreground and then invert.

  if (typeof color === 'undefined' || color === null) {
    return ''
  }

  return setAttributes([color + 10])
}

export function invert() {
  // Inverts the foreground and background colors.

  return `${ESC}[7m`
}

export function invertOff() {
  // Un-inverts the foreground and backgrund colors.

  return `${ESC}[27m`
}

export function startTrackingMouse() {
  return `${ESC}[?1002h`
}

export function stopTrackingMouse() {
  return `${ESC}[?1002l`
}

export function requestCursorPosition() {
  // Requests the position of the cursor.
  // Expect a stdin-result '\ESC[l;cR', where l is the line number (1-based),
  // c is the column number (also 1-based), and R is the literal character
  // 'R' (decimal code 82).

  return `${ESC}[6n`
}

export function enableAlternateScreen() {
  // Enables alternate screen:
  // "Xterm maintains two screen buffers.  The normal screen buffer allows
  // you to scroll back to view saved lines of output up to the maximum set
  // by the saveLines resource.  The alternate screen buffer is exactly as
  // large as the display, contains no additional saved lines."

  return `${ESC}[?1049h`
}

export function disableAlternateScreen() {
  return `${ESC}[?1049l`
}

export function measureColumns(text) {
  // Returns the number of columns the given text takes. Accounts for escape
  // codes (by not including them in the returned width).

  if (text.includes(ESC)) {
    text = text.replace(new RegExp(String.raw`${ESC}\[\??[0-9;]*.`, 'g'), '')
  }

  return wcwidth(text)
}

export function trimToColumns(text, cols) {
  // Trims off the end of the passed text so that its width doesn't exceed
  // the size passed in columns.

  let out = ''
  for (const char of text) {
    if (measureColumns(out + char) <= cols) {
      out += char
    } else {
      break
    }
  }
  return out
}

export function wrapToColumns(text, cols) {
  // Wraps a string into separate lines. Returns an array of strings, for
  // each line of the text.

  const lines = []
  const words = text.split(' ')

  let curLine = words[0]
  let curColumns = measureColumns(curLine)

  for (const word of words.slice(1)) {
    const wordColumns = measureColumns(word)
    if (curColumns + wordColumns > cols) {
      lines.push(curLine)
      curLine = word
      curColumns = wordColumns
    } else {
      curLine += ' ' + word
      curColumns += 1 + wordColumns
    }
  }

  lines.push(curLine)

  return lines
}

export function isANSICommand(buffer, code = null) {
  return (
    buffer[0] === 0x1b && buffer[1] === 0x5b &&
    (code ? buffer[buffer.length - 1] === code : true)
  )
}

export function interpret(text, scrRows, scrCols, {
  oldChars = null, oldLastChar = null,
  oldScrRows = null, oldScrCols = null,
  oldCursorRow = 1, oldCursorCol = 1, oldShowingCursor = true
} = {}) {
  // Interprets the given ansi code, more or less.

  const blank = {
    attributes: [],
    char: ' '
  }

  const chars = new Array(scrRows * scrCols).fill(blank)

  if (oldChars) {
    for (let row = 0; row < scrRows && row < oldScrRows; row++) {
      for (let col = 0; col < scrCols && col < oldScrCols; col++) {
        chars[row * scrCols + col] = oldChars[row * oldScrCols + col]
      }
    }
  }

  let showingCursor = oldShowingCursor
  let cursorRow = oldCursorRow
  let cursorCol = oldCursorCol
  let attributes = []

  for (let charI = 0; charI < text.length; charI++) {
    const cursorIndex = (cursorRow - 1) * scrCols + (cursorCol - 1)

    if (text[charI] === ESC) {
      charI++

      if (text[charI] !== '[') {
        throw new Error('ESC not followed by [')
      }

      charI++

      // Selective control sequences (look them up) - we can just skip the
      // question mark.
      if (text[charI] === '?') {
        charI++
      }

      const args = []
      let val = ''
      while (isDigit(text[charI])) {
        val += text[charI]
        charI++

        if (text[charI] === ';') {
          charI++
          args.push(val)
          val = ''
          continue
        }
      }
      args.push(val)

      // CUP - Cursor Position (moveCursor)
      if (text[charI] === 'H') {
        cursorRow = parseInt(args[0])
        cursorCol = parseInt(args[1])
      }

      // SM - Set Mode
      if (text[charI] === 'h') {
        if (args[0] === '25') {
          showingCursor = true
        }
      }

      // ED - Erase Display (clearScreen)
      if (text[charI] === 'J') {
        // ESC[2J - erase whole display
        if (args[0] === '2') {
          chars.fill(blank)
          charI += 3
          cursorCol = 1
          cursorRow = 1
        }

        // ESC[1J - erase to beginning
        else if (args[0] === '1') {
          for (let i = 0; i < cursorIndex; i++) {
            chars[i * 2] = ' '
            chars[i * 2 + 1] = []
          }
        }

        // ESC[0J - erase to end
        else if (args.length === 0 || args[0] === '0') {
          for (let i = cursorIndex; i < chars.length; i++) {
            chars[i * 2] = ' '
            chars[i * 2 + 1] = []
          }
        }
      }

      // RM - Reset Mode
      if (text[charI] === 'l') {
        if (args[0] === '25') {
          showingCursor = false
        }
      }

      // SGR - Select Graphic Rendition
      if (text[charI] === 'm') {
        const removeAttribute = attr => {
          if (attributes.includes(attr)) {
            attributes = attributes.slice()
            attributes.splice(attributes.indexOf(attr), 1)
          }
        }

        for (const arg of args) {
          if (arg === '0') {
            attributes = []
          } else if (arg === '22') { // Neither bold nor faint
            removeAttribute('1')
            removeAttribute('2')
          } else if (arg === '23') { // Neither italic nor Fraktur
            removeAttribute('3')
            removeAttribute('20')
          } else if (arg === '24') { // Not underlined
            removeAttribute('4')
          } else if (arg === '25') { // Blink off
            removeAttribute('5')
          } else if (arg === '27') { // Inverse off
            removeAttribute('7')
          } else if (arg === '28') { // Conceal off
            removeAttribute('8')
          } else if (arg === '29') { // Not crossed out
            removeAttribute('9')
          } else if (arg === '39') { // Default foreground
            for (let i = 0; i < 10; i++) {
              removeAttribute('3' + i)
            }
          } else if (arg === '49') { // Default background
            for (let i = 0; i < 10; i++) {
              removeAttribute('4' + i)
            }
          } else {
            attributes = attributes.concat([arg])
          }
        }
      }

      continue
    }

    chars[cursorIndex] = {
      char: text[charI], attributes
    }

    // Some characters take up multiple columns, e.g. Japanese text. Take
    // this into consideration when drawing.
    const charColumns = wcwidth(text[charI])
    cursorCol += charColumns

    // If the character takes up 2+ columns, treat columns past the first
    // one (where the character is) as empty. (Note this is different from
    // "blank", which represents an empty space character ' '.)
    for (let i = 1; i < charColumns; i++) {
      chars[cursorIndex + i] = {char: '', attributes: []}
    }

    if (cursorCol > scrCols) {
      cursorCol = 1
      cursorRow++
    }
  }

  // SPOooooOOoky diffing! -------------
  //
  // - Search for series of differences. This means a collection of characters
  //   which have different text or attribute properties.
  //
  // - Figure out how to print these differences. Move the cursor to the beginning
  //   character's row/column, then print the differences.

  const newChars = chars

  const differences = []

  if (oldChars === null) {
    differences.push(0)
    differences.push(newChars.slice())
  } else {
    const charsEqual = (oldChar, newChar) => {
      if (oldChar.char !== newChar.char) {
        return false
      }

      let oldAttrs = oldChar.attributes.slice()
      let newAttrs = newChar.attributes.slice()

      while (newAttrs.length) {
        const attr = newAttrs.shift()
        if (oldAttrs.includes(attr)) {
          oldAttrs.splice(oldAttrs.indexOf(attr), 1)
        } else {
          return false
        }
      }

      oldAttrs = oldChar.attributes.slice()
      newAttrs = newChar.attributes.slice()

      while (oldAttrs.length) {
        const attr = oldAttrs.shift()
        if (newAttrs.includes(attr)) {
          newAttrs.splice(newAttrs.indexOf(attr), 1)
        } else {
          return false
        }
      }

      return true
    }

    let curChars = null

    for (let i = 0; i < chars.length; i++) {
      const oldChar = oldChars[i]
      const newChar = newChars[i]

      // TODO: Some sort of "distance" before we should clear curDiff?
      // It may take *less* characters if this diff and the next are merged
      // (entering a single character is smaller than the length of the code
      // used to move past that character). Probably not very significant of
      // an impact, though.
      if (charsEqual(oldChar, newChar)) {
        curChars = null
      } else {
        if (curChars === null) {
          curChars = []
          differences.push(i, curChars)
        }

        curChars.push(newChar)
      }
    }
  }

  // Character concatenation -----------

  let lastChar = oldLastChar || {
    char: '',
    attributes: []
  }

  const result = []

  for (let parse = 0; parse < differences.length; parse += 2) {
    const i = differences[parse]
    const chars = differences[parse + 1]

    const col = i % scrCols
    const row = (i - col) / scrCols
    result.push(moveCursor(row, col))

    for (const char of chars) {
      const newAttributes = (
        char.attributes.filter(attr => !(lastChar.attributes.includes(attr)))
      )

      const removedAttributes = (
        lastChar.attributes.filter(attr => !(char.attributes.includes(attr)))
      )

      // The only way to practically remove any character attribute is to
      // reset all of its attributes and then re-add its existing attributes.
      // If we do that, there's no need to add new attributes.
      if (removedAttributes.length) {
        result.push(resetAttributes())
        result.push(`${ESC}[${char.attributes.join(';')}m`)
      } else if (newAttributes.length) {
        result.push(`${ESC}[${newAttributes.join(';')}m`)
      }

      result.push(char.char)

      lastChar = char
    }
  }

  // If anything changed *or* the cursor moved, we need to put it back where
  // it was before:
  if (result.length || cursorCol !== oldCursorCol || cursorRow !== oldCursorRow) {
    result.push(moveCursor(cursorRow, cursorCol))
  }

  // If the cursor is visible and wasn't before, or vice versa, we need to
  // show that:
  if (showingCursor !== oldShowingCursor) {
    if (showingCursor) {
      result.push(showCursor())
    } else {
      result.push(hideCursor())
    }
  }

  return {
    oldChars: newChars.slice(),
    oldLastChar: Object.assign({}, lastChar),
    oldScrRows: scrRows,
    oldScrCols: scrCols,
    oldCursorRow: cursorRow,
    oldCursorCol: cursorCol,
    oldShowingCursor: showingCursor,
    screen: result.join('')
  }
}