src/routing_spec.bend source

src/routing_spec.bend on the hub · documented module

import Baseimport ./contracts.bend as C# Independent pure specification; no implementation matching/selection helpers.def combine(first: C.Match, rest: C.Match) -> C.Match:  match first rest:    case C.Matched{Nil{}} other: other    case C.Matched{Con{p, Nil{}}} C.Matched{ps}: C.Matched{p <> ps}    case other other_rest: C.NoMatch{}def exact(same: Bool) -> C.Match:  match same:    case True{}: C.Matched{Nil{}}    case False{}: C.NoMatch{}def parameter(ok: Bool, name: String, value: String) -> C.Match:  match ok:    case True{}: C.Matched{[C.Param{name, value}]}    case False{}: C.NoMatch{}def nonempty(name: String, value: String) -> Bool:  match name value:    case SCon{h, t} SCon{v, vs}: True{}    case other other_value: False{}def part_kind(is_parameter: Bool, head: Char, +name: String, +value: String) -> C.Match:  match is_parameter:    case True{}: parameter(nonempty(name, value), name, value)    case False{}: exact(String.eq(SCon{head, name}, value))def part(pattern: String, +value: String) -> C.Match:  match pattern:    case SNil{}: exact(String.is_empty(value))    case SCon{+head, +name}:      part_kind(Char.is_eq(head, ':'), head, name, value)def segments(pattern: List<&2, String>, path: List<&2, String>) -> C.Match:  match pattern path:    case Nil{} Nil{}: C.Matched{Nil{}}    case p <> ps v <> vs: combine(part(p, v), segments(ps, vs))    case other other_path: C.NoMatch{}def path(pattern: String, value: String) -> C.Match:  segments(String.split(pattern, '/'), String.split(value, '/'))# Filter path matches, retaining table order and exact captured parameters.type Hit is Data:  Hit{route: C.Route, params: List<&2, C.Param>}def include(result: C.Match, route: C.Route, tail: List<&2, Hit>) -> List<&2, Hit>:  match result:    case C.NoMatch{}: tail    case C.Matched{params}: Hit{route, params} <> taildef hits(routes: List<&2, C.Route>, +value: String) -> List<&2, Hit>:  match routes:    case Nil{}: Nil{}    case +route <> tail:      match route:        case C.Route{id, method, pattern, protected, statuses}:          include(path(pattern, value), route, hits(tail, value))# Keep the last occurrence of each verb, without changing suffix order.def member(+verb: String, methods: List<&2, String>) -> Bool:  match methods:    case Nil{}: False{}    case m <> ms: Bool.or(String.eq(verb, m), member(verb, ms))def retain(duplicate: Bool, verb: String, methods: List<&2, String>) -> List<&2, String>:  match duplicate:    case True{}: methods    case False{}: verb <> methods# Two separate observations define the public specification: the first method# hit, and all path-hit methods deduplicated by their last occurrence.type First is Data:  Present{hit: Hit}  Absent{}def first_step(same: Bool, hit: Hit, suffix: First) -> First:  match same:    case True{}: Present{hit}    case False{}: suffixdef first(hits: List<&2, Hit>, +method: String) -> First:  match hits:    case Nil{}: Absent{}    case +hit <> tail:      match hit:        case Hit{C.Route{id, verb, pattern, protected, statuses}, params}:          first_step(String.eq(verb, method), hit, first(tail, method))def dedup_head(+verb: String, +suffix: List<&2, String>) -> List<&2, String>:  retain(member(verb, suffix), verb, suffix)def verb(route: C.Route) -> String:  match route:    case C.Route{id, method, pattern, protected, statuses}: methoddef allowed(hits: List<&2, Hit>) -> List<&2, String>:  match hits:    case Nil{}: Nil{}    case Hit{C.Route{id, +verb, pattern, protected, statuses}, params} <> tail:      dedup_head(verb, allowed(tail))def summary(first: First, methods: List<&2, String>) -> C.Selection:  match first:    case Present{Hit{route, params}}: C.Found{route, params}    case Absent{}:      match methods:        case Nil{}: C.Missing{}        case m <> ms: C.WrongMethod{m <> ms}def select(+routes: List<&2, C.Route>, +method: String, +value: String) -> C.Selection:  summary(first(hits(routes, value), method), allowed(hits(routes, value)))def empty(hits: List<&2, Hit>) -> Bool:  match hits:    case Nil{}: True{}    case h <> hs: False{}def absent(first: First) -> Bool:  match first:    case Absent{}: True{}    case Present{hit}: False{}def missing(selection: C.Selection) -> Bool:  match selection:    case C.Missing{}: True{}    case C.Found{route, params}: False{}    case C.WrongMethod{methods}: False{}def wrong(selection: C.Selection) -> Bool:  match selection:    case C.Missing{}: False{}    case C.Found{route, params}: False{}    case C.WrongMethod{methods}: True{}