Update readme with new features (mainly !if); cleared a few thinsg off of TODO

README.md

@@ -190,6 +190,55 @@ Will result in:
 MyFavouriteNumber: 1
 ```
 
+#### !if
+
+Conditionally include portions of the document.
+
+Expects to receive an array where the first element is a condition, the second is
+the value if the condition is true, and the third is the value if the condition
+is false.
+
+Expressions use postfix notation because this is a play project right now and
+it's both fun and easy to implement and my HP calculator demanded it. Bright side,
+you never have to worry about operator precedence!
+
+Example:
+
+```
+cnfpp:
+	variables:
+		LoadBalancerType: internal
+
+Resources:
+	MyLoadBalancer:
+		Subnet: !if
+			- LoadBalancerType "internal" eq
+			- subnet-1234
+			- subnet-6789
+```
+
+The true/false values can include maps/arrays/any other valid YAML.
+
+#### Expressions
+
+Expressions are composed of space separated values and operators. Value components
+are:
+
+* Numeric Literals: Any integer or float value.
+* String Literals: Any value enclosed in double quotes (`"`). A backslash can be
+  used to quote/escape literal quotes within the string.
+* Variables: Any non-quoted string consisting of letters and numbers (no leading
+  digit) is interpreted as a reference to one of the variables.
+* Operator: Currently supported comparison/logical operators are:
+	- eq: equal
+	- neq: not equal
+	- gt: greater than
+	- gte: greater than or equal
+	- lt: less than
+	- lte: less than or equal
+	- and: boolean and
+	- or: boolean or
+
 ## Usage
 
 ### Running
@@ -208,12 +257,5 @@ Note: Building is not required to run.
 ## TODO
 
 * Provision rendered templates directly to CloudFormation
-* Maybe look at implementing an actual dependency graph to make stuff like "multiple inheritance" a little cleaner.
-  E.g., if a single app stack pulls in multiple resources which all depend on `base.yaml`, don't reprocess base.yaml a
-  bunch of times but instead just realize that's the root and process it once.
 * Add flow control: `!if`, `!foreach`, etc
-* Extend variables to support arrays/maps. Probably write a helper or add a toArray on Node since we're having to
-  convert to/from dom nodes and arrays/maps all over the place.
-* Build an expression parser. Just to make everyone's life difficult, because it's fun and this is a toy project, and
-  also to avoid having to care about operator precedence let's do it all postfix? My HP50G would be proud.
 * Some sort of macro system would be good.