From 2af7a59592e4774c3fc9be7202285c44ba9a5c6f Mon Sep 17 00:00:00 2001
From: Joe Wreschnig <joe.wreschnig@gmail.com>
Date: Tue, 20 Apr 2010 22:21:09 -0700
Subject: [PATCH] If: Conditional actions.

---
 bulletml/parser.py             | 53 ++++++++++++++++++++++++
 examples/normal/twofire-if.xml | 75 ++++++++++++++++++++++++++++++++++
 2 files changed, 128 insertions(+)
 create mode 100644 examples/normal/twofire-if.xml

diff --git a/bulletml/parser.py b/bulletml/parser.py
index 653b90f..2075ac9 100644
--- a/bulletml/parser.py
+++ b/bulletml/parser.py
@@ -377,6 +377,58 @@ class Repeat(object):
     def __repr__(self):
         return "%s(%r, %r)" % (type(self).__name__, self.times, self.action)
 
+class If(object):
+    """Conditional actions."""
+
+    def __init__(self, cond, then, else_=None):
+        self.cond = cond
+        self.then = then
+        self.else_ = else_
+
+    def __getstate__(self):
+        if self.else_:
+            return [('cond', self.cond.expr),
+                    ('then', self.then),
+                    ('else', self.else_)]
+        else:
+            return [('cond', self.cond.expr), ('then', self.then)]
+
+    def __setstate__(self, state):
+        state = dict(state)
+        state["else_"] = state.pop("else", None)
+        state["cond"] = INumberDef(state["cond"])
+        self.__init__(**state)
+
+    @classmethod
+    def FromXML(cls, doc, element):
+        """Construct using an ElementTree-style element."""
+        else_ = None
+        for subelem in element.getchildren():
+            tag = realtag(subelem)
+            if tag == "cond":
+                cond = INumberDef(subelem.text)
+            elif tag == "then":
+                then = ActionDef.FromXML(doc, subelem)
+            elif tag == "else":
+                else_ = ActionDef.FromXML(doc, subelem)
+        try:
+            return cls(cond, then, else_)
+        except UnboundLocalError as exc:
+            raise ParseError(str(exc))
+
+    def __call__(self, owner, action, params, rank, created):
+        if self.cond(params, rank):
+            branch = self.then
+        else:
+            branch = self.else_
+
+        if branch:
+            actions, params = branch(params, rank)
+            child = action.__class__(owner, action, actions, params, rank)
+            owner.replace(action, child)
+            child.step(owner, created)
+            return True
+        
 class Accel(object):
     """Accelerate over some time."""
 
@@ -976,3 +1028,4 @@ ActionDef.CONSTRUCTORS = dict(
     untag=Untag,
     action=ActionDef,
     actionRef=ActionRef)
+ActionDef.CONSTRUCTORS["if"] = If
diff --git a/examples/normal/twofire-if.xml b/examples/normal/twofire-if.xml
new file mode 100644
index 0000000..ddc1b8f
--- /dev/null
+++ b/examples/normal/twofire-if.xml
@@ -0,0 +1,75 @@
+<?xml version="1.0" ?>
+<!DOCTYPE bulletml SYSTEM "http://www.asahi-net.or.jp/~cs8k-cyu/bulletml/bulletml.dtd">
+
+<bulletml xmlns="http://www.asahi-net.or.jp/~cs8k-cyu/bulletml"
+	  xmlns:py="http://code.google.com/p/python-bulletml/">
+
+  <action label="top">
+    <actionRef label="threefire">
+      <param>10 + 20 * $rank * $rand</param>
+    </actionRef>
+  </action>
+
+  <action label="threefire">
+    <fire>
+      <bulletRef label="dropper">
+	<param>$1</param>
+	<param>0</param>
+      </bulletRef>
+      <direction>0</direction>
+    </fire>
+    <py:if>
+      <py:cond>$rand > 0.5</py:cond>
+      <py:then>
+	<fire>
+	  <bulletRef label="dropper">
+	    <param>$1</param>
+	    <param>-90</param>
+	  </bulletRef>
+	  <direction type="sequence">-90</direction>
+	</fire>
+      </py:then>
+      <py:else>
+	<fire>
+	  <bulletRef label="dropper">
+	    <param>$1</param>
+	    <param>90</param>
+	  </bulletRef>
+	  <direction type="sequence">90</direction>
+	</fire>
+      </py:else>
+    </py:if>
+  </action>
+
+  <bullet label="dropper">
+    <speed>1</speed>
+    <action>
+      <wait>3</wait>
+      <changeSpeed>
+	<term>1</term>
+	<speed>0</speed>
+      </changeSpeed>
+      <changeDirection>
+	<term>1</term>
+	<direction type="relative">-$2</direction>
+      </changeDirection>
+      <wait>1</wait>
+      <repeat>
+	<times>$1</times>
+	<action>
+	  <fire>
+	    <bullet>
+	      <direction type="relative">0</direction>
+	      <speed type="absolute">1</speed>
+	    </bullet>
+	  </fire>
+	  <wait>4</wait>
+	</action>
+      </repeat>
+      <changeSpeed>
+	<term>1</term>
+	<speed>1</speed>
+      </changeSpeed>
+    </action>
+  </bullet>
+</bulletml>
-- 
2.30.2