Formula Parser Equip Vars Demo

Description

This page describes how to use the Formula Parser Equipment Variables Demo, provided in a sandbox (in Subversion)

Location

The Demo is in sandbox/EqVarDemo/PCGen and can be checked out from subversion as any other branch of PCGen. Please use build.xml (and ant) to build PCGen, as Gradle support may not be fully enabled in this branch.

General Comments and Limitations

When possible, use integers. The system is capable of doing integer arithmetic, so 1+2 will produce 3, whereas 1.0+2.0 may produce 2.9999999999999.

Known Limitations:

• Is not intended to cover unreasonably high numbers
• There is at least one UI problem, in that the UI doesn't realize that the PRExxx status of an EqMod can dynamically changes when another EqMod is added. The EqMod in question has to be selected to turn red.
• This system does not support variables across multiple heads (well, to be specific, variables are shared across an entire piece of equipment at the moment, so EqMods that use them to control what can be applied may not work correctly with double-headed weapons)

Please stick to variables that start with a-z or A-Z and have other characters that are letters or numbers. (They must NOT start with a number). Failure to follow this means bets are off as to behavior. Full checking of names for legality will occur at a later time.

New Game Mode MISC Info File Token

The following tokens are REQUIRED in the game mode to set the default value of a variable type:

DEFAULTVARIABLEVALUE:NUMBER|0
DEFAULTVARIABLEVALUE:POINT|0,0

New Campaign File Token

VARIABLE

VARIABLE: is a new Campaign file token (for PCC files). It is treated "recursively" like other tokens, e.g. TEMPLATE.

Limitations: It does not support PRExxx or INCLUDE/EXCLUDE.

Future Development: It is reasonable to expect PRExxx could be supported, it is unlikely that INCLUDE/EXCLUDE would be supported due to the nature of variables not being traditional objects (too much unique code)

New Variable File Tokens

LOCAL

LOCAL: is a token for the Variable files defined by the VARIABLE: PCC token. These have 2 arguments, the scope, and the variable name. For example:

LOCAL:EQUIPMENT|ModCount

Limitations:

• Only EQUIPMENT is supported.
• By Design: Must appear as the first token on a line

Known Issues: The variable names are not checked to ensure they are "character legal" (this is a statement about illegal characters like '*' not related to whether they were defined in a Variable LST file).

Future Development:

• Address Known Issues
• Resolve whether "EQUIPMENT" is actually the item on the line or whether it is "Equipment Variables" (how the code thinks internally). This is eventually a risk of tying closely the code and the data, so this requires consideration of how object types are defined (a much longer discussion than belongs here - please ask on _dev if you are interested)

EXPLANATION

EXPLANATION: is a free-text token (no parsing is really done) that is designed to describe why a variable exists

Limitations:

• By Design: Must not appear as the first token on a line

Behavior:

• Overwrites (as if someone would use it twice??)

Future Development

At least "GLOBAL" would be a future development item (though it would "default" to that, so the following variable file is valid:

MyGlobalVariable
GLOBAL:MyOtherGlobalVariable
LOCAL:EQUIPMENT|MyLocalVar

New Variable File REQUIREMENTS

The variable file performs 2 functions: (1) it identifies variable types (2) it identifies variables that can be used in the data

The following tokens are REQUIRED in variable file:

TYPE:NUMBER|VAR
TYPE:POINT|AREA

You may NOT define ANY variables until AFTER the TYPE: entry appears in the VAR file (yes, this is an issue we will need to figure out whether these definitions can appear elsewhere)

Note that the GLOBAL and LOCAL tokens today IMPLY VAR. Meaning

GLOBAL:MyOtherGlobalVariable

is (to the code) actually

GLOBAL:VAR|MyOtherGlobalVariable

Note this can be combined with the implied GLOBAL, so

MyGlobalVariable

is (to the code) actually

GLOBAL:VAR|MyGlobalVariable

We will need to decide if all these items can stay implied, but I believe they can.

Prerequisites

PREEQVARxxx exist as PRE tokens. All valid suffixes (LT, EQ, NEQ, etc.) are supported. Please see the PREVAR documentation if you are not familiar with the legal suffixes.

Syntax: PREEQVARxx:y,z

Limitations:

• Only Numbers (Integer or Decimal) or a single, legal variable name are supported as y and z.

Modify Token

Syntax

MODIFY:w|x|y|PRIORITY=z

w is the variable name as defined in the Variable LST file x is the modification type. Legal types are shown below. y is the modification (based on the type, see below) z is an OPTIONAL priority. If not specified, it is assumed to be zero.

Priority

Items are processed in a Natural Priority order. PRIORITY is used to order any modifiers, then a natural ordering is used. So:

MODIFY:Var|ADD|4
MODIFY:Var|MULTIPLY|5

are applied, the Multiplication will ALWAYS occur first, regardless of token order in the file. If you are unsure of natural order, use PRIORITY to control processing order.

Priority must be >= 0

Items are processed from the lowest priority to the highest (highest is applied last, so a SET with a high priority is applied last)

A clarification on natural ordering: it does NOT replace priority if not defined. The two priority comparisons (user priority and natural priority) are independent. So an item of user priority 1 and natural priority 3 will be processed before user priority 2 and natural priority 2, solely based on the user priority)

Legal Types

ADD

ADD takes a Numeric Argument. Must be a legal Integer or Double, no calculations are allowed.

The 'natural' priority is 3.

MULTIPLY

MULTIPLY takes a Numeric Argument. Must be a legal Integer or Double, no calculations are allowed.

The 'natural' priority is 2.

MAX

MAX takes a Numeric Argument. Must be a legal Integer or Double, no calculations are allowed.

This sets an upper bound on the value (a maximum that the value can be)

The 'natural' priority is 4.

MIN

MIN takes a Numeric Argument. Must be a legal Integer or Double, no calculations are allowed.

This sets a lower bound on the value (a minimum that the value can be)

The 'natural' priority is 5.

SET

SET takes a Numeric Argument. Must be a legal Integer or Double, no calculations are allowed.

This sets the value (any previous value is overwritten/ignored)

The 'natural' priority is 0.

SOLVE

The 'natural' priority is 6.

This calculates a new value, and equations using other variables are allowed. If you have a value that was previously modified from the default (or you want to enable that based on using a higher PRIORITY= then you should use the value() function to capture the existing value. Thus the following are equivalent:

MODIFY:Foo|ADD|4
MODIFY:Foo|SOLVE|value()+4

(Note that the ADD is preferred because it is smaller in memory and faster to process, but more complex calculations will obviously require SOLVE)

Functions Supported

The following functions are supported:

• min
• max
• ceil
• floor
• if
• abs
• round

If you have questions about the behavior, see the existing PCGen docs.

Walkthrough of the connections

Note the Game Mode MISCINFO file defines a default for NUMBER and POINT

Only items with a default value in the Misc Info file may be used as the first argument on the TYPE line in the variable file.

Therefore:

TYPE:NUMBER|VAR

Defines an internal "variable type" of "VAR" that holds numbers.

This is done because we may want something like:

TYPE:NUMBER|MOVEMENT

This allows us to have multiple, non-conflicting types of numbers in the data.

Once the second argument is used in a TYPE entry, then it can be used in other data, including LOCAL and GLOBAL in the variable file and MODIFY in other LST files. Items are referred to by the second argument, NOT the underlying type. So the following would be reasonable data:

TYPE:POINT|AREA
AREA|Face
MODIFY:AREA=Face|SET|10,10

Note that we are asking the data team to put the TYPE into the var file, but we are currently implying the Face in the code. This is so that we can "hide" the use of GLOBAL in the test (since that would cause a few confusing issues)

Note also that MODIFY CANNOT be used with the "=" in the first argument, so please don't try it! I am echoing long term intent, not immediate syntax.