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as edited this page Sep 30, 2017 · 5 revisions

Edit

The edit commands are implemented in as/edit. They are over-optimized which means there are a lot of bugs. One benefit however is performance.

Inserts and deletes are folded into writes. The compiler's output program only resizes the buffer once based on the net growth or shrinkage of the final text.

  • The input string is fed through a lexer and parser
  • The parser is the compiler, it generates a sequence of functions in parallel to the parsing process
  • The result is a callable go function that executes the program on a text.Editor
  • A program's run command wraps the given text.Editor and replaces its Insert and Delete methods, instead generating a structural transcript of inserts and deletes
  • The transcript of inserts and deletes are pipelined to an optimizing coalescer.
  • The coalescer optimizes the stream of inserts and deletes using a set of algebraic equivalence rules.
  • The optimized events are stored in a log
  • When the first pass of execution is complete, the log is full of instructions in the form i 1 2 &string("a")
  • The program evaluates the net direction of data change (growth or shrinkage) and resizes the real text.Editor
  • At this point, all of the inserts and deletes can be converted into writes that don't resize the buffer
  • This combination of steps linearizes the computation time for even unbearable constructions like ,x,.,d
  • The writes are executed on the real text.Editor in linear time with respect to the size of the buffer
  • The compiled program can be run again, without recompilation

Look

Look inspects the text around the cursor. It is triggered with mouse button 2. In standard Acme, issuing a look in the column tag or main tag is a no-op. In A, this fires a look event in all of the column's windows. If a look triggers in a grid tag, all columns issue the look event to their respective windows.

Install

Install interpolates an Edit command on every call to a window's SetOrigin or Refresh method. Combined with the 'h' subcommand this compiles an on-the fly structure highlighter for the given expression.

Install ,x,github,h

Notes

  • Install is not a standard Acme command (neither is h)
  • Install can not be chained
  • Colors can not be chosen
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