PuduLangLog.Expressions.Template

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

Purpose

Parses and renders expression templates: literal text, holes {expression:format}, and the directives #if, #else if, #else, #each … in …, #delimit, and #end.

Interface

Signatures

export type Node = TextNode(Str)
  | Hole(Syntax.Expression, Option[Str])
  | Choice(Array[Branch], Array[Node])
  | Each(Str, Option[Str], Syntax.Expression, Array[Node], Array[Node], Array[Node])

export type Branch = { condition: Syntax.Expression, body: Array[Node] }

export fn parse(text: Str) -> Result[Array[Node], Str]

export fn expressionsIn(nodes: &Array[Node]) -> Array[Syntax.Expression]

export fn render(nodes: &Array[Node], within: &Evaluator.Scope) -> Str

Linkage

• Requires: [[src/PuduLangLog]], [[src/PuduLangLog/Domain/Display]], [[src/PuduLangLog/Domain/Json]], [[src/PuduLangLog/Domain/Levels]], [[src/PuduLangLog/Expressions/Evaluator]], [[src/PuduLangLog/Expressions/Lexer]], [[src/PuduLangLog/Expressions/Parser]], [[src/PuduLangLog/Expressions/Syntax]], [[src/PuduLangLog/Expressions/Values]], Std.List.
• Consumed by: [[src/PuduLangLog/Expressions]].

Algorithm

1. Doubled braces are literal braces; a hole ends at the brace that closes it, skipping nested brackets and quoted text.
2. A hole's format follows its first top-level :.
3. @l renders through level monikers and @m through the message with JSON-style values; other scalars render under the format and collections as JSON.
4. #each x, i in source binds each element and its position, or each member name and value.

Negative Logic (Prohibited Paths)

• An unclosed hole or block is refused when parsing.

Edge Cases

• An undefined hole renders nothing; an empty #each renders its #else part.

Depth

DEPTH 0.7 (DEEP). Tested by test/PuduLangLog/Expressions/TemplateTest.

Grill Log

• Q: Why parse to nodes once? A: A sink formats every event; parsing per event would repeat the same work each time. _Rejected:_ interpreting the text on each render.

Referenced by

[[src/PuduLangLog/_MOC]] · [[src/PuduLangLog/Expressions]] · [[src/PuduLangLog/Expressions/Evaluator]] · [[src/PuduLangLog/Expressions/Lexer]] · [[src/PuduLangLog/Expressions/Parser]] · [[src/PuduLangLog/Expressions/Syntax]] · [[src/PuduLangLog/Expressions/Values]] · [[subsystems/Expressions]]