我应该如何为这种简单的玩具语言创建Vim语法？

Question

I have an extremely simple toy language for which I'd like to create a Vim syntax.

// A non-functional sample:

// "resolve" is the keyword here, though that's not a fixed part of the
// syntax.
$hostsys : resolve "host" "system"
// Since there's only one token to the right of the = here, it's an alias
// and not an operation.
$zero = 0
// An operation is analogous to a method call in a typical OO language.
// "toString" would be the keyword or method name here
$str = toString $someObject
// It's possible for there to be more or fewer than one lvalue on a
// directive or operation.
// 2 return values
$xp $yp = rotate $util $x $y 90
// No return values
= println $out $str

The major problem I seem to be running into is that this language doesn't have a fixed set of keywords, but rather the token at a certain position per line is treated as a keyword. I'm not sure where to look for examples of this.

Here is a fairly complete outline of the syntax:

program : line*

line : <start of line> WS* command? comment? <end of line>

command : operation | alias | directive

// Always at least one operand after operator
operation : (Register WS+)* '=' WS+ operator (WS+ operand)+ WS*

// No operator and only one "operand"
alias : Register WS+ '=' WS+ operand <not followed by WS+ operand> WS*

directive : (Register WS+)* ':' WS+ operator (WS+ operand)* WS*

operator : QuotedString | Register | bareword

operand : value

WS : /\s/

QuotedString : /"[^"]*"/

Register : /\$\S+/

BooleanLiteral : /true|false/

NoneLiteral : /none/

NumericLiteral : /-?\d+(\.\d+)?/

nonBarewordValue :
    QuotedString | Register | BooleanLiteral | NoneLiteral | NumericLiteral

Comment : "//" <any non-newline character>*

bareword : /\S+/ except {Comment, nonBarewordValue}

value : bareword | nonBarewordValue

In particular, the operator rule as it appears in directive and operation should be highlighted as a keyword instead of its normal role. Additionally, it should be possible to highlight the = in an alias differently from the = in an operation .

Have been running in circles on this one and decided it was time to ask someone more familiar with the dark arts. Thanks in advance.

Answer 1

just to give you an idea how to distinguish between those operation/alias keywords:

syn match alias /=\s*\w\+/ contains=alEqual
syn match operation /=\s*\w\+\ze\s\+\S\+/ contains=opEqual

syn match alEqual /=/ contained
syn match opEqual /=/ contained