Compile regexes lazyly.

Profiling shows that compiling the regexes takes most of the execution
time. Compiling them when needed instead of compiling all of them
upfront decreases execution time from 0.70 to 0.12 seconds.

   Ordered by: cumulative time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
      6/1    0.000    0.000    0.702    0.702 {built-in method builtins.exec}
        1    0.001    0.001    0.702    0.702 z80count.py:24(<module>)
        1    0.000    0.000    0.696    0.696 z80count.py:104(main)
        1    0.000    0.000    0.692    0.692 z80count.py:65(__init__)
        1    0.005    0.005    0.692    0.692 z80count.py:77(_load_table)
     1888    0.001    0.000    0.680    0.000 re.py:232(compile)
     1891    0.017    0.000    0.680    0.000 re.py:271(_compile)
     1631    0.009    0.000    0.647    0.000 sre_compile.py:759(compile)
     1631    0.006    0.000    0.325    0.000 sre_parse.py:919(parse)
3263/1631    0.008    0.000    0.312    0.000 sre_parse.py:417(_parse_sub)
     1631    0.003    0.000    0.306    0.000 sre_compile.py:598(_code)
3266/1632    0.115    0.000    0.305    0.000 sre_parse.py:475(_parse)
16700/1631    0.112    0.000    0.246    0.000 sre_compile.py:71(_compile)
   131243    0.061    0.000    0.086    0.000 sre_parse.py:164(__getitem__)
     1631    0.007    0.000    0.057    0.000 sre_compile.py:536(_compile_info)
18331/3262    0.043    0.000    0.053    0.000 sre_parse.py:174(getwidth)
    48041    0.018    0.000    0.047    0.000 sre_parse.py:254(get)
     9741    0.030    0.000    0.039    0.000 sre_compile.py:276(_optimize_charset)
    52307    0.033    0.000    0.033    0.000 sre_parse.py:233(__next)
    13432    0.010    0.000    0.029    0.000 sre_compile.py:423(_simple)
173223/156520    0.021    0.000    0.026    0.000 {built-in method builtins.len}
   237477    0.024    0.000    0.024    0.000 {method 'append' of 'list' objects}
   142999    0.022    0.000    0.022    0.000 {built-in method builtins.isinstance}
     9741    0.016    0.000    0.019    0.000 sre_compile.py:249(_compile_charset)
    43579    0.014    0.000    0.018    0.000 sre_parse.py:160(__len__)
    30678    0.010    0.000    0.014    0.000 sre_parse.py:172(append)
     1631    0.001    0.000    0.012    0.000 sre_parse.py:96(closegroup)
     1631    0.004    0.000    0.011    0.000 enum.py:827(__and__)
    19310    0.009    0.000    0.011    0.000 sre_parse.py:286(tell)
    35044    0.011    0.000    0.011    0.000 {built-in method builtins.min}
    10767    0.007    0.000    0.010    0.000 sre_parse.py:343(_escape)
    23891    0.006    0.000    0.008    0.000 sre_parse.py:249(match)
    16701    0.008    0.000    0.008    0.000 sre_parse.py:111(__init__)
     3270    0.003    0.000    0.006    0.000 enum.py:281(__call__)

1 files changed, 2 insertions, 3 deletions

diff --git a/z80count.py b/z80count.py
index 54929dd..a465b3d 100755
--- a/z80count.py
+++ b/z80count.py
@@ -112,6 +112,8 @@ class Parser(object):
         if mnemo is None or mnemo not in self._table:
             return None
         for entry in self._table[mnemo]:
+            if "cregex" not in entry:
+                entry["cregex"] = re.compile(r"^\s*" + entry["regex"] + r"\s*(;.*)?$", re.I)
             if entry["cregex"].search(line):
                 return entry
         return None
@@ -122,9 +124,6 @@ class Parser(object):
         with open(table_file, "rt") as fd:
             table = json.load(fd)
 
-        for i in table:
-            i["cregex"] = re.compile(r"^\s*" + i["regex"] + r"\s*(;.*)?$", re.I)
-
         table.sort(key=lambda o: o["w"])
         res = {}
         for i in table: