finished new variable grabbler

variable_grabbler.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-import os, sys, json, traceback
+import os, sys, json, traceback, subprocess
 
 # Definitions
 def stdout(string, end='\n', flush=False):
@@ -9,31 +9,34 @@ def stdout(string, end='\n', flush=False):
 def stderr(string, end='\n', flush=False):
     print(string, end=end, file=sys.stderr, flush=flush)
 
+exit_codes = {
+  "normal exit":            0,
+  "wrong usage":            1,
+  "error while processing": 2
+}
+
 stderr("Variable Grabbler - version 5.0_pre1\n--------------------------------------------------------------------------------")
 ################################################################################
 # Chnages in this version:
-# - port to Python 3
+# - complete rewrite in Python 3
 # - output to stdout instead of rewriting the file
 #===============================================================================
 # Full documentation: tbd
 #===============================================================================
-# Exit codes:
-# 0: normal exit
-# 1: wrong usage
-# 2: error while processing
 
 # Command line input handling
 usage = "Usage: python3 "+sys.argv[0]+" <macro config file> <file to be processed>"
 if not len(sys.argv)==3:
     stderr("E: Wrong amount of arguments.")
     stderr(usage)
-    sys.exit(1)
+    sys.exit(exit_codes["wrong usage"])
 if sys.argv[1] == sys.argv[2]:
     stderr("E: Both input files are the same.")
     stderr(usage)
-    sys.exit(1)
+    sys.exit(exit_codes["wrong usage"])
 
-stderr("I: Reading macro definitions... ", end="")
+# load macros into a dict
+stderr("I: Reading macro definitions... ")
 macros = {}
 try:
     if os.path.isfile(sys.argv[1]):
@@ -44,13 +47,47 @@ try:
         macros = json.loads(sys.stdin.read())
     else:
         stderr("E: Not a valid file: "+sys.argv[1])
-        sys.exit(2)
+        sys.exit(exit_codes["error while processing"])
 except:
     stderr("E: An exception occurred while trying to read macro definitions:")
     traceback.print_exc()
-    sys.exit(2)
-stderr("Done.")
+    sys.exit(exit_codes["error while processing"])
 
+# process "file" and "exec" macros
+stderr("I: Loading templates and processing commands...")
+for macro in macros:
+    if macros[macro][0] == "file":
+        if os.path.isfile(macros[macro][1]):
+            try:
+                stderr("I: Loading template: " + macro)
+                template = open(macros[macro][1], "r")
+                macros[macro] = template.read()
+                template.close()
+            except:
+                stderr("E: An exception occurred while trying to read the template:")
+                traceback.print_exc()
+                sys.exit(exit_codes["error while processing"])
+        else:
+            stderr("E: Macro \"" + macro + "\": template \"" + macros[macro][1] + "\" is not a valid file.")
+            sys.exit(exit_codes["error while processing"])
+    elif macros[macro][0] == "exec":
+        try:
+            stderr("I: Running command: " + macro)
+            process = subprocess.Popen(macros[macro][1], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            process_stdout, process_stderr = process.communicate()
+            macros[macro] = process_stdout
+            if len(process_stderr) > 0:
+                stderr("Output on stderr:\n"+process_stderr)
+            if not process.returncode == 0:
+                stderr("E: Command execution failed with exit code "+str(process.returncode))
+                sys.exit(exit_codes["error while processing"])
+        except:
+            stderr("E: An exception occurred while trying to process the command:")
+            traceback.print_exc()
+            sys.exit(exit_codes["error while processing"])
+
+# open file to be processed and iterate over it
+stderr("I: Preparing to process input file...")
 try:
     input_file = sys.stdin
     if os.path.isfile(sys.argv[2]):
@@ -60,8 +97,12 @@ try:
         pass
     else:
         stderr("E: Not a valid file: "+sys.argv[2])
-        sys.exit(2)
+        sys.exit(exit_codes["error while processing"])
+    # make the magic happen
+    stderr("I: Processing input file...")
     for line in input_file:
+        for macro in macros:
+            line = line.replace("%" + macro + "%", str(macros[macro]))
         stdout(line, end="")
     # close input file if it's not sys.stdin, assume sys.stdin is being handled for us
     if not input_file==sys.stdin:
@@ -69,4 +110,4 @@ try:
 except:
     stderr("E: An exception occured while processing " + input_file.name + ":")
     traceback.print_exc()
-    sys.exit(2)
+    sys.exit(exit_codes["error while processing"])