Faulty D Dependency Logic in SCons

Question

I've tracked down a bug in the dependency logic for D sources in SCons.

The self.cre regexp import\s+(?:\[a-zA-Z0-9_.\]+)\s*(?:,\s*(?:\[a-zA-Z0-9_.\]+)\s*)*; in SCons.Scanner.D doesn't cover patterns such as...

import IMPORT_PATH : SYMBOL;

...only:

import IMPORT_PATH;

Same with the self.cre2 regexp (?:import\s)?\s*([a-zA-Z0-9_.]+)\s*(?:,|;) two lines later.

I believe both the self.cre and self.cre2 regexps need to be fixed; but I don't quite understand how they are related. My guess is that self.cre matches the whole import statements and self.cre2 matches parts of them. Am I correct? If so self.cre2 needs to be corrected to handle cases such as:

import X, Y, Z;

Does anyone have any idea how to fix the regexps so that they handle these cases?

My first try is to change

p = 'import\s+(?:[a-zA-Z0-9_.]+)\s*(?:,\s*(?:[a-zA-Z0-9_.]+)\s*)*;'

to

p = 'import\s+(?:[a-zA-Z0-9_.]+)\s*(?:,\s*(?:[a-zA-Z0-9_.]+)(?:\s*:\s*[a-zA-Z0-9_.]+)??\s*)*;'

I've tried debugging this but in vain.

Python:

import re
p = 'import\s+(?:[a-zA-Z0-9_.]+)\s*(?:,\s*(?:[a-zA-Z0-9_.]+)\s*)*;'

re.match(p, "import first;") # match
re.match(p, "import first : f;") # no match

p2 = 'import\s+(?:[a-zA-Z0-9_.]+)\s*(?:,\s*(?:[a-zA-Z0-9_.]+)(?:\s*:\s*[a-zA-Z0-9_.]+)??\s*)*;'

re.match(p2, "import first;") # match
re.match(p2, "import first : f;") # no match but should match
re.match(p2, "import first : f, second : g;") # no match but should match

J0e3gan · Accepted Answer · 2015-02-21T20:35:32.237

Short Answer

To handle all the cases you have outlined, try the following twist on your changes to the (self.cre) pattern:

import\s+(?:[a-zA-Z0-9_.]+)\s*(?:(?:\s+:\s+[a-zA-Z0-9_.]+\s*)?(?:,\s*(?:[a-zA-Z0-9_.]+)(?:\s*:\s*[a-zA-Z0-9_.]+)??\s*)*)*;

Regular expression visualization

Debuggex Demo

Digging Deeper

self.cre vs. self.cre2

Yes, the find_include_names method...

def find_include_names(self, node):
    includes = []
    for i in self.cre.findall(node.get_text_contents()):
        includes = includes + self.cre2.findall(i)
    return includes

...confirms the relationship between self.cre and self.cre2 that you guessed: the former matches entire import statements, and the latter matches (and captures) modules therein. (Note the middle (...) capture group in self.cre2 vs. (?:...) non-capture groups elsewhere throughout self.cre and self.cre2.)

self.cre

Picking up where your Python snippet left off...

import re

import1 = "import first;"
import2 = "import first : f;"
import3 = "import first : f, second : g;"


p = 'import\s+(?:[a-zA-Z0-9_.]+)\s*(?:,\s*(?:[a-zA-Z0-9_.]+)\s*)*;'

pm1 = re.match(p, import1) # match
if pm1 != None:
    print "p w/ import1 => " + pm1.group(0)

pm2 = re.match(p, import2) # no match
if pm2 != None:
    print "p w/ import2 => " + pm2.group(0)


p2 = 'import\s+(?:[a-zA-Z0-9_.]+)\s*(?:,\s*(?:[a-zA-Z0-9_.]+)(?:\s*:\s*[a-zA-Z0-9_.]+)??\s*)*;'

p2m1 = re.match(p2, import1) # match
if p2m1 != None:
    print "p2 w/ import1 => " + p2m1.group(0)

p2m2 = re.match(p2, import2) # no match but should match
if p2m2 != None:
    print "p2 w/ import2 => " + p2m2.group(0)

p2m3 = re.match(p2, import3) # no match but should match
if p2m3 != None:
    print "p2 w/ import3 => " + p2m3.group(0)

..., we get the following expected output for p and p2 attempts to match the import statements:

p w/ import1 => import first;
p2 w/ import1 => import first;

Now consider p2prime, wherein I have made changes to arrive at the pattern I suggested above:

import re

import1 = "import first;"
import2 = "import first : f;"
import3 = "import first : f, second : g;"
import4 = "import first, second, third;"

p2prime = 'import\s+(?:[a-zA-Z0-9_.]+)\s*(?:(?:\s+:\s+[a-zA-Z0-9_.]+\s*)?(?:,\s*(?:[a-zA-Z0-9_.]+)(?:\s*:\s*[a-zA-Z0-9_.]+)??\s*)*)*;'

p2pm1 = re.match(p2prime, import1) # match
if p2pm1 != None:
    print "p2prime w/ import1 => " + p2pm1.group(0)

p2pm2 = re.match(p2prime, import2) # now a match
if p2pm2 != None:
    print "p2prime w/ import2 => " + p2pm2.group(0)

p2pm3 = re.match(p2prime, import3) # now a match
if p2pm3 != None:
    print "p2prime w/ import3 => " + p2pm3.group(0)

p2pm4 = re.match(p2prime, import4) # now a match
if p2pm4 != None:
    print "p2prime w/ import4 => " + p2pm4.group(0)

With the updated pattern (p2prime) we get the following desired output for its attempts to match the import statements:

p2prime w/ import1 => import first;
p2prime w/ import2 => import first : f;
p2prime w/ import3 => import first : f, second : g;
p2prime w/ import4 => import first, second, third;

This is a pretty lengthy and involved pattern: so I would not be surprised to find opportunities to fine tune it further; but it does what you want and should provide a solid basis for fine tuning.

self.cre2

For self.cre2, similarly try the following pattern:

(?:import\s)?\s*(?:([a-zA-Z0-9_.]+)(?:\s+:\s+[a-zA-Z0-9_.]+\s*)?)\s*(?:,|;)