reorganise python interface

packages/python/swig/yapi.py

@@ -0,0 +1,120 @@
+
+import yap
+import os.path
+import sys
+# debugging support.
+import pdb
+from collections import namedtuple
+
+yap_lib_path = os.path.dirname(__file__)
+
+use_module = namedtuple( 'use_module', 'file')
+bindvars = namedtuple( 'bindvars', 'list')
+library = namedtuple( 'library', 'list')
+v = namedtuple( '_', 'slot')
+
+
+
+def numbervars(  engine, l ):
+    return engine.fun(bindvars(l))
+
+def query_prolog(engine, s):
+
+    def answer(q):
+        try:
+            return q.next()
+        except Exception as e:
+            print(e.args[1])
+            return False
+
+    #
+    # construct a query from a one-line string
+    # q is opaque to Python
+    q = engine.query(s)
+    # vs is the list of variables
+    # you can print it out, the left-side is the variable name,
+    # the right side wraps a handle to a variable
+    # pdb.set_trace()
+    vs = q.namedVars()
+    #pdb.set_trace()
+    # atom match either symbols, or if no symbol exists, sttrings, In this case
+    # variable names should match strings
+    #for eq in vs:
+    #    if not isinstance(eq[0],str):
+    #        print( "Error: Variable Name matches a Python Symbol")
+    #        return
+    ask = True
+    # launch the query
+    while answer(q):
+        # this new vs should contain bindings to vars
+        vs=  q.namedVars()
+        print( vs )
+        gs = numbervars( engine, vs)
+        print(gs)
+        i=0
+        # iterate
+        for eq in gs:
+            name = eq[0]
+            binding = eq[1]
+            # this is tricky, we're going to bind the variables in the term so thay we can
+            # output X=Y. The Python way is to use dictionares.
+            #Instead, we use the T function to tranform the Python term back to Prolog
+            if name != binding:
+                print(name + " = " + str(binding))
+            #ok, that was Prolog code
+        print("yes")
+        # deterministic = one solution
+        if q.deterministic():
+            # done
+            q.close()
+            return
+        if ask:
+            s = input("more(;),  all(*), no(\\n), python(#) ?").lstrip()
+            if s.startswith(';') or s.startswith('y'):
+                continue
+            elif s.startswith('#'):
+                try:
+                    exec(s.lstrip('#'))
+                except:
+                    raise
+            elif s.startswith('*') or s.startswith('a'):
+                ask = False
+                continue
+            else:
+                break
+    print("No (more) answers")
+    q.close()
+    return
+
+
+def live():
+    args = yap.YAPEngineArgs()
+    args.setYapLibDir(yap_lib_path)
+    args.setYapShareDir(yap_lib_path)
+    #args.setYapPrologBootFile(os.path.join(yap_lib_path."startup.yss"))
+    engine = yap.YAPEngine( args )
+    engine.goal( use_module( library('yapi') ) )
+    loop = True
+    while loop:
+        try:
+            s = input("?- ")
+            if not s:
+                loop = False
+            query_prolog(engine, s)
+        except SyntaxError as err:
+            print("Syntax Error error: {0}".format(err))
+        except EOFError:
+            return
+        except RuntimeError as err:
+            print("YAP Execution Error: {0}".format(err))
+        except ValueError:
+            print("Could not convert data to an integer.")
+        except:
+            print("Unexpected error:", sys.exc_info()[0])
+            raise
+    engine.close()
+#
+# initialize engine
+# engine = yap.YAPEngine();
+# engine = yap.YAPEngine(yap.YAPParams());
+live()