Ejercicio 9

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)