Changeset 110:602b33270077

Timestamp:

02/20/10 16:48:19 (7 months ago)

Author:

Roger Gammans <rgammans@…>

Branch:

default

Message:

More grammar improvements, allow arbitary defrefences , and remove old stuff.

• Arbitray length field specifiers such as a:b:c:d now possible. = useful for dereference now across link objects. = dereferencing collection attributes (new feature due soon).

• Removal of old FreeFormObject? syntax elements, and their deps.

Files:

• MysteryMachine/parsetools/grammar.py (modified) (7 diffs)

MysteryMachine/parsetools/grammar.py

@@ -2 +2 @@
 
 ###Grammar stuff
-from pyparsing import Forward, Regex,Optional,ZeroOrMore, QuotedString , Literal, Word, alphas , nums , printables  , CharsNotIn , stringEnd
-from functools import partial
+from pyparsing import Forward, OneOrMore, QuotedString , Literal, Word, alphas , nums , stringEnd
 
 import logging
@@ -11 +10 @@
 
 #Tokens
-openExpr   =   Literal("${")
-closeExpr  =   Literal("}")
 seperator  =   Literal(":")
 queryOp    =   Literal("?")
@@ -19 +16 @@
 
 #Characters to avoid ?,:,/,!,= (eg other literals)
-identifier =   Word("_" + alphas + nums)
-objectName =   identifier.copy()
-fieldName  =   identifier.copy()
-ObjectId   =   Word(nums)
-NonExpr    =   CharsNotIn("$")
-
-ExprLimit  =   Regex("[^ \n\t]*[ \n\t]")
+identifier =   Word("-" + "_" + alphas + nums)
 LiteralVal =   QuotedString('"') 
 
@@ -33 +24 @@
     # Productions
     cfoperator  =   equalsOp ^ notequalsOp
-    ObjectUID   =   Optional(objectName + seperator + ObjectId)
+  
+    pathElement=    seperator + identifier
+    RelSpec    =    OneOrMore(pathElement)
+    AbsSpec    =    identifier + RelSpec
 
-    NamedField  =   ObjectUID + seperator +fieldName
-    ExprField   =   ObjectUID ^  \
-                NamedField
+    ExprField  =    AbsSpec ^ RelSpec
 
     ExprText   =    Forward()   
@@ -47 +39 @@
                       LiteralVal  )
 
-    #Error      =   openExpr + ExprLimit 
-
-    #These production are about handling expressions
-    # in run of text. The use is mainly historical.
-    Expr       =   openExpr + ExprText + closeExpr
-    
-    textEle    =   NonExpr  ^ \
-                   Expr 
-       
-    text       =   ZeroOrMore(textEle)
-
-
     ## Functions for parsing.
-
-    def getField(s,loc,toks):
-        modlogger.debug( "getField(%s)\n" % toks)
-        field=toks[2]
-        obj=toks[0]
-        return obj[field]
-
-
     def doBool(s,loc,toks):
         modlogger.debug( "getbol\n")
@@ -81 +53 @@
                 return toks[4]
 
-    def initFromParse(s,loc,toks):
-        modlogger.debug( "Creating from :'%s'->%s (current=%s)\n" %(s,str(toks),repr(home)))
-        isSelf=len(toks)==0
-        if isSelf:         return home 
-        elif home is None: return None
-        else:              return home.get_root().get_object(toks[0],toks[2])
+    def ExprFieldAction(s,loc,toks):
+        #In this case our walk will fail so
+        # just return None as an invalid thang.
+        if home is None: return None
+
+        #Determine whether abs or rel and
+        # find our origin.
+        # We use the home  objct - or
+        # derefernce the object if it is an absolute reference.
+        # - we can't just get the category because there is (currently)
+        #   no object which represents those , but we can get an object
+        #   and the grammar is specified such that an object must be spcified
+        #   not just a category`
+        if toks[0] == ":":
+            origin  = home
+            path    = toks[1:]
+        else:
+            origin  = home.get_root().get_object(toks[0],toks[2])
+            path    = toks[4:]
+       
+        #Walk along the attributes
+        for ele in path:
+            if ele != ":": #Skip ':' as grammar noise.
+                origin = origin[ele]
+
+        return origin
+    
 
     #def gotError(s,loc,toks):
@@ -93 +86 @@
     ## Bind functions to parse actions
     
-    NamedField.setParseAction(getField)
-
+    ExprField.setParseAction(ExprFieldAction)
     BoolExpr.setParseAction(doBool)
     QueryExpr.setParseAction(doQuery)
-    Expr.setParseAction(lambda s,loc,tok:tok[1])
-    #Error.setParseAction(gotError)
 
-    ObjectUID.setParseAction(initFromParse)
-    
+    ExprText.enablePackrat()
+    ExprText.validate()
     return ExprText + stringEnd