Add Fall.vim

1 files changed, 80 insertions, 0 deletions

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+" Falling motions for Vim. "Falling" means moving the cursor down until it hits
+" text that doesn't match a pattern.
+
+" Returns an expression to be used in normal mode that results in the falling
+" motion. The semantics are as follows:
+"
+" The motion moves in the direction given by a:dir (which must be 'j' or 'k').
+" The motion moves while the character under the cursor does not match the
+" pattern, then it moves while the character under the cursor matches the
+" pattern stopping when the character under the cursor does not match the
+" pattern once again.
+"
+" ex.
+"
+" fall#fall('j', '^\s*$')
+"
+" for
+"
+" | t⌷is is some text
+" | this is some other text
+" |
+" |
+" | this is some bottom text
+" | this is some other bottom text
+"
+" will return an expression to update the cursor position to:
+"
+" | this is some text
+" | this is some other text
+" |
+" |
+" | t⌷is is some bottom text
+" | this is some other bottom text
+"
+" This works pretty well for navigating around languages that use indentation
+" and lack braces for bodies, i.e. vimscript, ruby. Less well for python, but
+" still okay.
+function! fall#fall(dir, pattern) abort
+  let i = 0
+  let n = 0
+
+  if a:dir == 'j'
+    let delta = 1
+  else
+    let delta = -1
+  endif
+
+  let line = line('.')
+  let column = col('.')
+  let c = v:count
+  if c == 0
+    let c = 1
+  endif
+
+  while i < c
+    let match = matchstr(getline(line), '\%' . column . 'c.')
+
+    while ! (match =~ a:pattern)
+      let n += 1
+      let line += delta
+      if line <= 0 || line >= line('$')
+        return "m'" . n . a:dir
+      endif
+      let match = matchstr(getline(line), '\%' . column . 'c.')
+    endwhile
+
+    while (match =~ a:pattern)
+      let n += 1
+      let line += delta
+      if line <= 0 || line >= line('$')
+        return "m'" . n . a:dir
+      endif
+      let match = matchstr(getline(line), '\%' . column . 'c.')
+    endwhile
+
+    let i += 1
+  endwhile
+
+  return "m'" . n . a:dir
+endfunction!