Ejercicio 9

exercises/ex04/ex04.py

@@ -1,4 +1,4 @@
-# Exercise 1
+# Exercise 4
 # 1. Getting help with -help or -h.
 # 2. A least three arguments that are flags, meaning they don’t take an extra
 #    argument but simply putting them on the command line turns something on.
@@ -10,12 +10,12 @@
 import argparse
 
 parser = argparse.ArgumentParser()
-parser.add_argument('filename')
-parser.add_argument('-o1', '--opt1')
-parser.add_argument('-o2', '--opt2')
-parser.add_argument('-o3', '--opt3')
-parser.add_argument('-f1', '--flag1', action='store_true')
-parser.add_argument('-f2', '--flag2', action='store_true')
-parser.add_argument('-f3', '--flag3', action='store_true')
+parser.add_argument("filename")
+parser.add_argument("-o1", "--opt1")
+parser.add_argument("-o2", "--opt2")
+parser.add_argument("-o3", "--opt3")
+parser.add_argument("-f1", "--flag1", action="store_true")
+parser.add_argument("-f2", "--flag2", action="store_true")
+parser.add_argument("-f3", "--flag3", action="store_true")
 args = parser.parse_args()
 print(args)

exercises/ex05/ex05.py

@@ -1,13 +1,15 @@
-# Exercise 2
+# Exercise 5
 # 1. cat command
 
 import argparse
 from pathlib import Path
 
 parser = argparse.ArgumentParser()
-parser.add_argument('paths', nargs="+", type=Path)
-parser.add_argument('-b', '--number-nonblank', default=False, action="store_true")
-parser.add_argument('-n', '--number', default=False, action="store_true")
+parser.add_argument("paths", nargs="+", type=Path)
+parser.add_argument(
+    "-b", "--number-nonblank", default=False, action="store_true"
+)
+parser.add_argument("-n", "--number", default=False, action="store_true")
 args = parser.parse_args()
 count = 1
 rest = 0
@@ -15,16 +17,16 @@ out = []
 
 for path in args.paths:
     if path.is_file():
-        for line in open(path, 'r').readlines():
+        for line in open(path, "r").readlines():
             blank = len(line.strip()) == 0 and args.number_nonblank
             if blank:
-                out.append({"ln": 0, "txt": ''})
+                out.append({"ln": 0, "txt": ""})
             else:
                 out.append({"ln": count, "txt": line.rstrip()})
                 count += 1
 
 for el in out:
-    line = ''
+    line = ""
     blank = len(el["txt"].strip()) == 0 and args.number_nonblank
     if args.number and not blank:
         total_width = len(str(out[-1]["ln"] - rest))

exercises/ex06/ex06.py

@@ -1,4 +1,4 @@
-# Exercise 2
+# Exercise 6
 # 1. find command
 
 import sys

exercises/ex07/ex07.py

@@ -1,4 +1,4 @@
-# Exercise 2
+# Exercise 7
 # 1. grep command
 
 import re
@@ -40,9 +40,9 @@ def grep(path, args):
 
 
 parser = argparse.ArgumentParser()
-parser.add_argument('paths', nargs="+", type=Path)
-parser.add_argument('-i', '--ignore-case', default=False, action="store_true")
-parser.add_argument('-E', '--extended-regexp', default=False, type=str)
+parser.add_argument("paths", nargs="+", type=Path)
+parser.add_argument("-i", "--ignore-case", default=False, action="store_true")
+parser.add_argument("-E", "--extended-regexp", default=False, type=str)
 
 if len(sys.argv) > 1:
     if sys.argv[1] != "-E" and sys.argv[1] != "-i":

exercises/ex08/ex08.py

@@ -1,4 +1,4 @@
-# Exercise 2
+# Exercise 8
 # 1. cut command
 
 import re
@@ -31,9 +31,9 @@ def parse(fields):
 
 
 parser = argparse.ArgumentParser()
-parser.add_argument('stream', default=sys.stdin, nargs="?")
-parser.add_argument('-d', '--delimiter', default=False, type=str)
-parser.add_argument('-f', '--fields', type=str, required=True)
+parser.add_argument("stream", default=sys.stdin, nargs="?")
+parser.add_argument("-d", "--delimiter", default=False, type=str)
+parser.add_argument("-f", "--fields", type=str, required=True)
 args = parser.parse_args()
 
 for line in args.stream:

exercises/ex09/ex09.py

@@ -0,0 +1,56 @@
+# Exercise 9
+# 1. sed command
+
+import re
+import sys
+import argparse
+from pathlib import Path
+
+
+def check(expression, exp):
+    error = False
+    if (
+        expression[-1] not in "/g"
+        or exp[0] not in "s"
+        or len(exp) not in range(3, 5)
+        or (expression[-1] in "g" and len(exp) != 4)
+        or (expression[-1] in "/" and len(exp) == 4)
+    ):
+        error = True
+    if error:
+        print(f"sed: expresión «{expression}» inválida")
+        sys.exit(1)
+
+
+def parse(expression):
+    count = 0
+    exp = list(filter(None, expression.split("/")))
+    check(expression, exp)
+    if len(exp) == 3:
+        count = 1
+    return {
+        "rgx": re.compile(exp[1]),
+        "rep": exp[2],
+        "n": count,
+    }
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument("stream", default=sys.stdin, nargs="*")
+parser.add_argument(
+    "-e", "--expression", required=True, type=str, action="append"
+)
+args = parser.parse_args()
+res = ""
+
+for exp in args.expression:
+    exp = parse(exp)
+    for stream in args.stream:
+        if isinstance(args.stream, list):
+            stream = Path(stream).read_text()
+        else:
+            stream = stream.strip()
+        if res == "":
+            res = stream
+        res = re.sub(exp["rgx"], exp["rep"], res, count=exp["n"])
+print(res)