cvex ← {space} ##.find string               ⍝ Lines containing string(s) ⍵.

Find returns a 2-column matrix of character vectors, one row for each occurrence
of [string] in each variable, function or operator in [space]. If the left argu-
ment is omitted, the current space is assumed.

If [string] is a nested vector, those lines containing each of the substrings in
order  are  reported.  For example: (find '<<' '>>') would find lines containing
sequences such as <<this>> but not those containing >>that<<.

The  first  column  in  each row of the result is the full name of the object in
which a match was found and the second column, the "line" containing the match.

Notice  that  [find]  can be used in conjunction with →refs← to search an entire
namespace tree.

Variables  are searched row-wise, so line numbers on variables correspond to the
display of the variable given by: {⎕←⍵}saw var.

Examples:

      find'⍴⍴'
 #.ambiv[8]     2>⍴⍴cr:shy←''                   ⍝ derived or primitive: quit.
 #.disp[60]     0=opt×⍴⍴⍵:hz                ⍝ undecorated or scalar ⍕⍵: char,
 #.disp[68]     0=opt×⍴⍴⍵:vt hz                 ⍝ scalar or no decoration.
 #.disp[71]     rows←(¯1+3⌊⍴⍴⍵)⊃vt rsig'⍒'      ⍝ high rank decorator overrides.
 #.display[17]  axes←{(-2⌈⍴⍴⍵)↑1+×⍴⍵}                   ⍝ Array axis types.
 #.subs[2]      0=⍴⍴⍵:⊃(⍵≡fm)⌽⍵(⊂to)                ⍝ special case scalar argt.
 #.subs[5]      1<⍴⍴⍵:↑(↓⍺)∇¨↓⍵                 ⍝ high rank: split.

      ⎕se.NumEd find'⎕IO'
 ⎕SE.NumEd.numed[0]    {name}numed msg;SPACE;NAME;OVAL;IO;⎕IO;⎕ML  ⍝ Numeric Editor
 ⎕SE.NumEd.numed[5]    IO←SPACE⍎'⎕IO'
 ⎕SE.NumEd.numed[6]    ⎕ML ⎕IO←0 1
 ⎕SE.NumEd.SelIndx[2]  rslt←(fm-⎕IO)∘+¨⍳to-fm-1

      ↑⍪/{⍵ find'⎕DQ'}¨refs ⎕se
 ⎕SE.cbtop.TB_POPUP[7]  ⎕DQ'popup'
 ⎕SE.tools.ftse[14]     'S0'⎕WC pps ⋄ ⎕DQ'S0'
 ⎕SE.NumEd.mbox[6]      'Mbox'⎕WC prps ⋄ ⎕DQ'Mbox'
 ⎕SE.NumEd.numed[10]    ⎕DQ''
 ⎕SE.NumEd.SaveAs[4]    ⎕DQ obid

    6 2↑ notes find' →' '← '    ⍝ lines with ' →' followed by '← '
 #.notes.ambiv[8]      conjunction with →refs← to ambivalize all functions and operators in a namespace
 #.notes.avl[9]        See →BST←
 #.notes.avl[92]       follows the →fibonacci← sequence and for an AVL tree of height ⍵ is:
 #.notes.avl[281]      [avl]  uses  the standard →BST← methods for search, insertion, and node removal.
 #.notes.contents[10]  │ ··· related function →goo← is a ···
 #.notes.date[6]       Optional  left argument {g} specifies the day number of the →Gregorian_calendar←

Some technical points:

Find  avoids  name clashes by having an operand function _outside_ the main body
of code, from whence it executes ⎕NC, ⎕NL, ⎕CR, etc.

    ⍺{                                  ⍝ Avoid name clashes by executing
        ⍺⍺⍎⍵                            ⍝ expression in target space out-
    }{                                  ⍝ side main code body.
        exec←⍺⍺                         ⍝ External execute.
        ···
        exec'⎕NL 2 3 4'                 ⍝ Names of vars, fns and ops.

The line in [find]:

        tag←(exec'⍕⍺⍺'){⍺⍺,'.',⍵}       ⍝ Space-tagging function.

defines  a  function by binding a left operand to an operator in the same way as
sum←+/.  The operand expression is evaluated only once at definition time rather
than each time the resulting function is called. This can have clear performance
benefits for non-trivial expressions. In the above cases, binding the operand in
this  way avoids having to name it or pass it as an additional argument to where
the  function will be called. An alternative coding would be to "glue" the value
to the left of the function using composition and reference it as '⍺':

        tag←(exec'⍕⍺⍺')∘{⍺,'.',⍵}       ⍝ Space-tagging function.

There  is  little  to choose between these alternatives,  except that the former
defines an ambi-valent function allowing a future extension to pass a left argu-
ment, whereas the latter defines a strictly monadic function.

The  same  technique  is  employed with subfunction "match", where both left and
right operands are bound.

See also: refs saw filefind rows

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