Q2 prep

Q2/Artefacts/fspow.py

@@ -0,0 +1,64 @@
+# main.py
+"""
+Parse and execute statements either in stdin or in file
+"""
+
+import sys
+
+from antlr4 import *
+from fspowLexer import fspowLexer
+from fspowParser import fspowParser
+# from fspowListener import fspowListener
+# from antlr4.tree.Trees import Trees
+from TreesUser import TreesUser
+from Q2.Artefacts.fspowVisitorUser import fspowVisitorUser
+
+
+def main(argv):
+    # argv[1] s/be name of source file
+    # if missing, use stdin
+    if len(argv) == 1:
+        # StdinStream is a standard ANTLR class read by the lexer
+        # (It is not a file descriptor)        
+        inpstream = StdinStream()
+    else:
+        inpname = argv[1]
+        # FileStream is a standard ANTLR class read by the lexer
+        # (It is not a file descriptor)        
+        inpstream = FileStream(inpname)
+
+    
+
+    # The lexer analyses the characters on inpstream and produces tokens 
+    lexer = fspowLexer(inpstream)
+    # .. on the token stream (belonging to a standard ANTLR class)
+    tokstream = CommonTokenStream(lexer)
+
+    # The parser produces an abstract syntax tree
+    parser = fspowParser(tokstream)
+    # When we execute the parse, we need to give it the starting rule of our grammar,
+    # which in our case is 'start' (as defined in fspow.g4),
+    # so here we invoke the method named after this rule: start()
+    tree = parser.prog()
+    
+    # print the parse tree
+    #print(TreesUser.toStringTree(tree, None, parser))
+    print(TreesUser.PrettyPrint(tree, None, parser))
+
+    visitor = fspowVisitorUser()
+    visitor.visit(tree)
+    
+    # The listener defines the actions to take upon entering an exiting nodes for 
+    # specific tokens on the AST
+    # listener = fspowListener()
+    
+    # A ParseTreeWalker is annother standard ANTLR class, that performs a walk on the AST
+    # walker = ParseTreeWalker()
+
+    # Get the tree walker to perform a walk on the AST, getting the listener to perform
+    # the appropriate actions
+    # walker.walk~(listener, tree)
+
+
+if __name__ == '__main__':
+    main(sys.argv)