Crate pocopine_expr 

Template expression parser + AST. Per RFC-012.

This crate owns the pure half of pocopine’s expression pipeline — lexer, parser, AST. The runtime evaluator (pocopine_core::expr::evaluate) and the proc-macro validator (pocopine_macros::for_plan, RFC 054) both depend on this crate.

Splitting parser from evaluator lets the macro crate validate template expressions at cargo check time without pulling in wasm-bindgen / web-sys (host-incompatible).

Hand-rolled recursive descent so:

• the wasm bundle doesn’t pay for a parser-combinator crate,
• errors carry structured spans a future .poco language server can consume directly (no second parse),
• the AST is trivially re-evaluable — the runtime caches it once per directive setup and walks it on every change.

Grammar (operator precedence, lowest → highest):

expr       := stmt_seq
stmt_seq   := stmt ( ';' stmt )*       // RFC-024
stmt       := assign | ternary
assign     := path '=' ternary         // RFC-024
ternary    := logic_or ( '?' expr ':' expr )?
logic_or   := logic_and ( '||' logic_and )*
logic_and  := equality  ( '&&' equality  )*
equality   := relation  ( ( '==' | '!=' ) relation )*
relation   := additive  ( ( '<=' | '<' | '>=' | '>' ) additive )*
additive   := unary     ( '+' unary )*
unary      := '!' unary | primary
primary    := literal | path | call | '(' expr ')'
call       := ident '(' ( ternary ( ',' ternary )* )? ')'   // RFC-024
literal    := string | number | 'true' | 'false' | 'null'
string     := '"' [^"]* '"' | "'" [^']* "'"
number     := /-?\d+(\.\d+)?/
path       := ident ( '.' ident )*
ident      := /[A-Za-z_$][A-Za-z0-9_$]*/

Structs

ParseError

Spanned

Enums

BinOp

Expr

Literal

Functions

parse

Parse src into a reusable AST. Returns structured errors with byte spans so a future .poco LSP can surface them without a second parse.

Type Aliases

Span

Byte-range span into the original source string.