View/Edit #29:end_expression

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1:  ":end_expression(string[,stop_at])"
2:  "  assumes string starts with an expression; returns the index of the last char in expression or 0 if string appears not to be an expression.  Expression ends at any character from stop_at which occurs at top level."
3:  string = args[1]
4:  stop_at = {@args, " "}[2]
5:  gone = 0
6:  paren_stack = ""
7:  inquote = 0
8:  search = top_level_search = "[][{}()\"" + strsub(stop_at, "]", "") + "]"
9:  paren_search = "[][{}()\"]"
10: while (m = match(string, search))
11:   char = string[m[1]]
12:   string[1..m[2]] = ""
13:   gone = gone + m[2]
14:   if (char == "\"")
15:     "...skip over quoted string..."
16:     char = "\\"
17:     while (char == "\\")
18:       if (!(m = match(string, "%(\\.?%|\"%)")))
19:         return 0
20:       endif
21:       char = string[m[1]]
22:       string[1..m[2]] = ""
23:       gone = gone + m[2]
24:     endwhile
25:   elseif (index("([{", char))
26:     "... push parenthesis..."
27:     paren_stack[1..0] = char
28:     search = paren_search
29:   elseif (i = index(")]}", char))
30:     if (paren_stack && "([{"[i] == paren_stack[1])
31:       "... pop parenthesis..."
32:       paren_stack[1..1] = ""
33:       search = paren_stack ? paren_search | top_level_search
34:     else
35:       "...parenthesis mismatch..."
36:       return 0
37:     endif
38:   else
39:     "... stop character ..."
40:     return gone - 1
41:   endif
42: endwhile
43: return !paren_stack && gone + length(string)

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