Initial working sed. I mean, yeah, working.

ex49_sed/ed/ed.py

@@ -1,4 +1,5 @@
 import sys
+import re
 import ed
 from ed.scanner import Scanner
 from ed.parser import EdParser
@@ -62,10 +63,16 @@ def quit(self):
         sys.exit(0)
 
     def read(self, file_name, address=None):
-        self.lines += open(file_name).readlines()
+        self.lines += [x.rstrip() for x in open(file_name).readlines()]
 
     def subst(self, pattern, replace, start=None, end=None):
-        pass
+        repat = re.compile(pattern)
+        new_lines = []
+
+        for line in self.lines:
+            new_lines.append(repat.sub(replace, line))
+
+        self.lines = new_lines
 
     def write(self, file_name=None):
         file_name = file_name or self.file_name

ex49_sed/ed/parser.py

@@ -51,6 +51,8 @@ def root(self):
             self.write()
         elif start == 'QUIT':
             self.buffer.quit()
+        elif start == 'SUBST':
+            self.subst()
         elif start == 'INTEGER':
             # this is an address
             self.address()
@@ -115,3 +117,9 @@ def join(self):
         self.match('JOIN')
         self.buffer.join(*self.calc_range())
 
+    def subst(self):
+        self.match('SUBST')
+        pat_tok = self.match('PATTERN')[1]
+        _, pattern, replace, _ = pat_tok.split('/')
+        self.buffer.subst(pattern, replace)
+

ex49_sed/ed/scanner.py

@@ -12,11 +12,13 @@ class Scanner(object):
     L(r'^w', 'WRITE'),
     L(r'^j', 'JOIN'),
     L(r'^q', 'QUIT'),
+    L(r'^s', 'SUBST'),
     L(r"^[0-9]+", "INTEGER"),
     L(r"^\+", "PLUS"),
     L(r"^\-", "MINUS"),
     L(r"^\s+", "SPACE"),
     L(r"^,", "COMMA"),
+    L(r'/.*/.*/', 'PATTERN'), # won't work totally
     L(r'^.*', "FILE_NAME"), # terrible regex
     ]
 

ex49_sed/run.py

@@ -1,13 +1,23 @@
 import readline
 import sys
+import argparse
 from ed import ed
 
+parser = argparse.ArgumentParser()
+parser.add_argument("infile", type=str, help="Input file.")
+parser.add_argument("-e", type=str, help="The script.")
+parser.add_argument("-f", type=str, help="A file script.", default=None)
+parser.add_argument("-n", action="store_true")
+args = parser.parse_args()
+
 buffer = ed.Buffer()
+buffer.edit(args.infile)
 
-while True:
-    try:
-        line = input("> ")
+if args.e:
+    ed.process(args.e, buffer)
+elif args.f:
+    lines = (x.strip() for x in open(args.f).readlines())
+    for line in lines:
         ed.process(line, buffer)
-    except EOFError: 
-        print()
-        sys.exit(0)
+
+print("\n".join(buffer.lines))