PuduLangLog.Expressions.Evaluator

type: module path: "@root/src/PuduLangLog/Expressions/Evaluator.pudu" fidelity: Active grammar: "[[grammar/pudu]]" depth_score: 0.7 depth_status: DEEP tags: [module, expressions] aliases: [PuduLangLog.Expressions.Evaluator]

Purpose

Evaluates an expression tree against an event: names, built-in properties, members, indexers, wildcards, operators, literals, and conditionals.

Interface

Signatures

export type Scope = { event: Log.Event, locals: Array[(Str, Log.Value)], now: Log.Timestamp, referenced: Array[Str] }

export fn scopeOf(event: &Log.Event, now: Log.Timestamp) -> Scope

export fn evaluate(expression: &Syntax.Expression, within: &Scope) -> Option[Log.Value]

Linkage

• Requires: [[src/PuduLangLog]], [[src/PuduLangLog/Domain/Display]], [[src/PuduLangLog/Domain/EventId]], [[src/PuduLangLog/Domain/Levels]], [[src/PuduLangLog/Domain/Properties]], [[src/PuduLangLog/Expressions/Functions]], [[src/PuduLangLog/Expressions/Syntax]], [[src/PuduLangLog/Expressions/Values]], Std.Decimal, Std.List, Std.Math.Float, Std.Option.
• Consumed by: [[src/PuduLangLog/Expressions]] and [[src/PuduLangLog/Expressions/Template]].

Algorithm

1. A name is a bound local first, then a built-in (@t, @m, @mt, @l, @x, @p, @i, @r, @tr, @sp), then an event property.
2. and and or treat anything but true as false and are never undefined.
3. A comparison or call over [?] or [*] is evaluated once per element and joined with any or all.
4. Arithmetic is exact except ^, which answers a float.
5. Rest() answers the properties the template does not name; Rest(true) also leaves out those the message names.

Negative Logic (Prohibited Paths)

• Division or remainder by zero is undefined.

Edge Cases

• A wildcard over something that is not a collection is false.

Depth

DEPTH 0.7 (DEEP). Tested by test/PuduLangLog/ExpressionsTest.

Grill Log

• Q: Why evaluate wildcards by rewriting the node per element? A: It keeps one evaluator for every operator and function. _Rejected:_ a separate quantified evaluator per operator.

Referenced by

[[src/PuduLangLog/_MOC]] · [[src/PuduLangLog/Expressions]] · [[src/PuduLangLog/Expressions/Functions]] · [[src/PuduLangLog/Expressions/Syntax]] · [[src/PuduLangLog/Expressions/Template]] · [[src/PuduLangLog/Expressions/Values]] · [[subsystems/Expressions]]