PuduLangLog.Expressions.Parser

type: module path: "@root/src/PuduLangLog/Expressions/Parser.pudu" fidelity: Active grammar: "[[grammar/pudu]]" depth_score: 0.6 depth_status: MEDIUM tags: [module, expressions] aliases: [PuduLangLog.Expressions.Parser]

Purpose

Reads tokens into an expression tree by precedence: conditionals, or, and, not, comparisons and like/in/is null, sums, products, powers, unary minus, and member access.

Interface

Signatures

export fn parse(text: Str) -> Result[Syntax.Expression, Str]

export fn expressionAt(found: &Array[Lexer.Token], start: Int) -> Step

Linkage

• Requires: [[src/PuduLangLog]], [[src/PuduLangLog/Expressions/Lexer]], [[src/PuduLangLog/Expressions/Syntax]], Std.Decimal, Std.List, Std.Set.
• Consumed by: [[src/PuduLangLog/Expressions]] and [[src/PuduLangLog/Expressions/Template]].

Algorithm

1. parse reads one expression and refuses any token left after it.
2. ^ is right-associative; -2 ^ 2 is (-2) ^ 2.
3. Whole numbers become integers; numbers with a point become exact decimals.
4. expressionAt reads one expression from any token, which is how template holes stop at their format's :.

Negative Logic (Prohibited Paths)

• No expression is answered for text with unread tokens.

Edge Cases

• An empty text ends too soon.

Depth

DEPTH 0.6 (MEDIUM). Tested by test/PuduLangLog/ExpressionsTest.

Grill Log

• Q: Why recursive descent? A: Precedence reads directly off the function chain, and each level is small enough to test through the public entry point. _Rejected:_ an operator-precedence table.

Referenced by

[[src/PuduLangLog/_MOC]] · [[src/PuduLangLog/Expressions]] · [[src/PuduLangLog/Expressions/Lexer]] · [[src/PuduLangLog/Expressions/Syntax]] · [[src/PuduLangLog/Expressions/Template]] · [[subsystems/Expressions]]