mirror of
https://github.com/overleaf/overleaf.git
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261 lines
7.7 KiB
CoffeeScript
261 lines
7.7 KiB
CoffeeScript
# An alternate composable implementation for text. This is much closer
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# to the implementation used by google wave.
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#
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# Ops are lists of components which iterate over the whole document.
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# Components are either:
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# A number N: Skip N characters in the original document
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# {i:'str'}: Insert 'str' at the current position in the document
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# {d:'str'}: Delete 'str', which appears at the current position in the document
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#
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# Eg: [3, {i:'hi'}, 5, {d:'internet'}]
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#
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# Snapshots are strings.
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p = -> #require('util').debug
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i = -> #require('util').inspect
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exports = if WEB? then {} else module.exports
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exports.name = 'text-composable'
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exports.create = -> ''
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# -------- Utility methods
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checkOp = (op) ->
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throw new Error('Op must be an array of components') unless Array.isArray(op)
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last = null
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for c in op
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if typeof(c) == 'object'
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throw new Error("Invalid op component: #{i c}") unless (c.i? && c.i.length > 0) or (c.d? && c.d.length > 0)
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else
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throw new Error('Op components must be objects or numbers') unless typeof(c) == 'number'
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throw new Error('Skip components must be a positive number') unless c > 0
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throw new Error('Adjacent skip components should be added') if typeof(last) == 'number'
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last = c
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# Makes a function for appending components to a given op.
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# Exported for the randomOpGenerator.
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exports._makeAppend = makeAppend = (op) -> (component) ->
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if component == 0 || component.i == '' || component.d == ''
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return
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else if op.length == 0
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op.push component
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else if typeof(component) == 'number' && typeof(op[op.length - 1]) == 'number'
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op[op.length - 1] += component
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else if component.i? && op[op.length - 1].i?
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op[op.length - 1].i += component.i
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else if component.d? && op[op.length - 1].d?
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op[op.length - 1].d += component.d
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else
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op.push component
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# checkOp op
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# Makes 2 functions for taking components from the start of an op, and for peeking
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# at the next op that could be taken.
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makeTake = (op) ->
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# The index of the next component to take
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idx = 0
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# The offset into the component
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offset = 0
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# Take up to length n from the front of op. If n is null, take the next
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# op component. If indivisableField == 'd', delete components won't be separated.
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# If indivisableField == 'i', insert components won't be separated.
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take = (n, indivisableField) ->
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return null if idx == op.length
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#assert.notStrictEqual op.length, i, 'The op is too short to traverse the document'
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if typeof(op[idx]) == 'number'
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if !n? or op[idx] - offset <= n
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c = op[idx] - offset
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++idx; offset = 0
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c
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else
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offset += n
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n
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else
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# Take from the string
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field = if op[idx].i then 'i' else 'd'
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c = {}
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if !n? or op[idx][field].length - offset <= n or field == indivisableField
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c[field] = op[idx][field][offset..]
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++idx; offset = 0
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else
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c[field] = op[idx][field][offset...(offset + n)]
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offset += n
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c
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peekType = () ->
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op[idx]
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[take, peekType]
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# Find and return the length of an op component
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componentLength = (component) ->
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if typeof(component) == 'number'
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component
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else if component.i?
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component.i.length
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else
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component.d.length
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# Normalize an op, removing all empty skips and empty inserts / deletes. Concatenate
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# adjacent inserts and deletes.
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exports.normalize = (op) ->
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newOp = []
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append = makeAppend newOp
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append component for component in op
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newOp
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# Apply the op to the string. Returns the new string.
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exports.apply = (str, op) ->
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p "Applying #{i op} to '#{str}'"
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throw new Error('Snapshot should be a string') unless typeof(str) == 'string'
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checkOp op
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pos = 0
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newDoc = []
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for component in op
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if typeof(component) == 'number'
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throw new Error('The op is too long for this document') if component > str.length
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newDoc.push str[...component]
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str = str[component..]
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else if component.i?
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newDoc.push component.i
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else
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throw new Error("The deleted text '#{component.d}' doesn't match the next characters in the document '#{str[...component.d.length]}'") unless component.d == str[...component.d.length]
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str = str[component.d.length..]
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throw new Error("The applied op doesn't traverse the entire document") unless '' == str
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newDoc.join ''
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# transform op1 by op2. Return transformed version of op1.
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# op1 and op2 are unchanged by transform.
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exports.transform = (op, otherOp, side) ->
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throw new Error "side (#{side} must be 'left' or 'right'" unless side == 'left' or side == 'right'
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checkOp op
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checkOp otherOp
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newOp = []
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append = makeAppend newOp
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[take, peek] = makeTake op
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for component in otherOp
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if typeof(component) == 'number' # Skip
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length = component
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while length > 0
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chunk = take(length, 'i')
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throw new Error('The op traverses more elements than the document has') unless chunk != null
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append chunk
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length -= componentLength chunk unless typeof(chunk) == 'object' && chunk.i?
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else if component.i? # Insert
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if side == 'left'
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# The left insert should go first.
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o = peek()
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append take() if o?.i
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# Otherwise, skip the inserted text.
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append(component.i.length)
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else # Delete.
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#assert.ok component.d
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length = component.d.length
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while length > 0
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chunk = take(length, 'i')
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throw new Error('The op traverses more elements than the document has') unless chunk != null
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if typeof(chunk) == 'number'
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length -= chunk
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else if chunk.i?
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append(chunk)
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else
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#assert.ok chunk.d
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# The delete is unnecessary now.
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length -= chunk.d.length
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# Append extras from op1
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while (component = take())
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throw new Error "Remaining fragments in the op: #{i component}" unless component?.i?
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append component
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newOp
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# Compose 2 ops into 1 op.
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exports.compose = (op1, op2) ->
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p "COMPOSE #{i op1} + #{i op2}"
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checkOp op1
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checkOp op2
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result = []
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append = makeAppend result
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[take, _] = makeTake op1
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for component in op2
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if typeof(component) == 'number' # Skip
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length = component
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while length > 0
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chunk = take(length, 'd')
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throw new Error('The op traverses more elements than the document has') unless chunk != null
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append chunk
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length -= componentLength chunk unless typeof(chunk) == 'object' && chunk.d?
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else if component.i? # Insert
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append {i:component.i}
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else # Delete
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offset = 0
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while offset < component.d.length
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chunk = take(component.d.length - offset, 'd')
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throw new Error('The op traverses more elements than the document has') unless chunk != null
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# If its delete, append it. If its skip, drop it and decrease length. If its insert, check the strings match, drop it and decrease length.
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if typeof(chunk) == 'number'
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append {d:component.d[offset...(offset + chunk)]}
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offset += chunk
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else if chunk.i?
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throw new Error("The deleted text doesn't match the inserted text") unless component.d[offset...(offset + chunk.i.length)] == chunk.i
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offset += chunk.i.length
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# The ops cancel each other out.
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else
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# Delete
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append chunk
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# Append extras from op1
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while (component = take())
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throw new Error "Trailing stuff in op1 #{i component}" unless component?.d?
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append component
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result
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invertComponent = (c) ->
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if typeof(c) == 'number'
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c
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else if c.i?
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{d:c.i}
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else
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{i:c.d}
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# Invert an op
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exports.invert = (op) ->
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result = []
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append = makeAppend result
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append(invertComponent component) for component in op
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result
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if window?
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window.ot ||= {}
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window.ot.types ||= {}
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window.ot.types.text = exports
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