python examples added

python/minidraw.py

@@ -0,0 +1,51 @@
+# minimal drawing from natural language input: just draw one square or circle
+# presupposes 'gf -make DrawEng.gf'
+
+import pgf
+from graphics import *
+
+# we assume this abstract syntax
+absmodule = "Draw"
+
+# change this to change input language
+langname = absmodule + "Eng"
+
+def execute(command,win):
+  "interpret drawCommand; other commands ignored"
+  fun,args = command.unpack()
+
+  if fun == "drawCommand":
+    obj = shape(args[0])
+    obj.draw(win)
+  else:
+    print("command not available")
+
+    
+def shape(obj):
+  "draw Shape, ignoring given colour and size in this simple example"
+  fun,args = obj.unpack()    
+  sh,xx = args[2].unpack()
+  
+  if sh == "circle_Shape":
+    shap = Circle(Point(300,300),200)
+  elif sh == "square_Shape":
+    shap = Rectangle(Point(200,200),Point(600,600))
+  else:
+    shap = None
+    
+  return shap
+
+def main():
+  "execute one line of input, quit by second Enter"
+  win = GraphWin("GF Draw", 1000, 1000)
+  gr  = pgf.readPGF(absmodule + ".pgf")
+  eng = gr.languages[langname]
+  line = input()
+  px = eng.parse(line.lower())
+  p,tree = px.__next__()
+  execute(tree,win)
+  input()
+
+main()
+
+