grep exercise

python/COMMENTS.md

@@ -2,7 +2,7 @@
 
 This page represents all my comments from my solutions currently hosted on [Exercism.io](https://exercism.io/). You can view my profile [here](https://exercism.io/profiles/Xevion).
 The reason for this is simply to have a place where I can collect my comments, as well as just have some fun with Python and webscraping. Exercise file and exercise submission links will be provided for each and every exercise.
-This file is for the **Python** track, contains **47** submissions, **17** of which have comments. This file was built on **23-07-2019** at **23:47:58 UTC**.
+This file is for the **Python** track, contains **48** submissions, **18** of which have comments. This file was built on **24-07-2019** at **04:03:49 UTC**.
 
 ## Word Count
 
@@ -233,6 +233,12 @@ I forgot that a couple things could be omitted, and decided to trim the nouns so
 
 
 
+## Grep
+
+[Link to File](./grep/grep.py) | [Link to Submission](https://exercism.io/tracks/python/exercises/grep/solutions/c5d464b7392248d6adaab310e49803f5)
+
+I liked this exercise honestly. I learned about some new modules and methods, for example, while trying to create the invert flag, I was looking into how to negate the matching function, and the `functools` module allows one to create a wrapper that can negate any function you pass through it.
+
 ## Tournament
 
 [Link to File](./tournament/tournament.py) | [Link to Submission](https://exercism.io/tracks/python/exercises/tournament/solutions/6617ee41fac443be992d3090e650a16e)

python/grep/grep.py

@@ -1,2 +1,51 @@
+from functools import partial
+
+all_flags = ['n', 'l', 'i', 'v', 'x', 'm'] # m for multiple files
+
+# Main grep function that works on multiple files
 def grep(pattern, flags, files):
-    pass
+    # Parse the flags into a dictionary
+    flags = [flag.strip('-').strip() for flag in flags.split()]
+    flags = {k : k in flags for k in all_flags}
+    flags['m'] = len(files) > 1
+    # Parse all the files given and then concatenate into a string
+    res = [grep_individual(pattern, flags, filename) for filename in files]
+    res = '\n'.join(list(filter(None, res))) # Filters out empty strings
+    return res + '\n' if len(res) > 0 else ''
+
+# Matching function with options for case, full match and inversion
+def match(subtext, text, case=True, full=False, invert=False):
+    if not case:
+        subtext, text = subtext.lower(), text.lower()
+    res = (subtext == text) if full else (subtext in text)
+    return not res if invert else res
+
+# Function for processing against a individual file
+def grep_individual(pattern, flags, filename):
+    # Create a local matching function using partial with the flags set
+    localmatch = partial(match, case=not flags['i'], full=flags['x'], invert=flags['v'])
+    text = open(filename, 'r').read()
+    result = []
+    if not flags['l']:
+        for i, line in enumerate(text.split('\n')):
+            if localmatch(pattern, line):
+                pieces = [line]
+                # Add number to beginning
+                if flags['n']:
+                    pieces.insert(0, str(i + 1))
+                # If multiple files, add the file name to the front furthermore
+                if flags['m']:
+                    pieces.insert(0, filename)
+                # Kind of a funky way to be doing it, but it's alright.
+                res = ':'.join(pieces)
+                result.append(res)
+        return '\n'.join(result)
+    # File name only flags
+    elif flags['l']:
+        for line in text.split('\n'):
+            # Returns as soon as a match is found
+            if localmatch(pattern, line):
+                return filename
+        return ''
+
+print(grep("may", "-n -m", ['grep_test.py']))