fn fieldsOf(v: Json) -> Array<JsonField>
An object's fields in document order, or [] for anything else.
std/jsondec
42 exports, from std/jsondec.vyrn.
The untyped half of fromJson, and the generator of the typed half.
jsonDecoders writes the typed half per target type. What it writes reads the source once through a JsonReader and decodes each value into its slot; it builds no Json tree. It calls this module for the reader, Issues, paths and scalar decoders. Decoding accumulates: a decoder records its failure and returns, and a composite constructs only when every part succeeded. So every decoder returns an Array<T> of zero or one element; empty means the issue is already recorded. Option<T> cannot serve: with T = Option<U> it has no wire form. Every message is the canonical wording, byte for byte. A refused document yields its json.parse Issue alone, and a record's Issues follow its members' declaration order, whatever the document's key order.
The tree accessors (fieldsOf, fieldAt and the rest) serve programs that read a Json from parseJson.
Dependencies
The import graph shows the whole library.
fn itemsOf(v: Json) -> Array<Json>
An array's items, or [] for anything else.
fn numText(v: Json) -> String
A number's raw source text, or "" for anything else.
fn hasField(fs: Array<JsonField>, key: String) -> Bool
Whether an object carries key at all (a present null is still present).
fn fieldAt(fs: Array<JsonField>, key: String) -> Json
The value of key, or JNull when absent.
fn elemAt(items: Array<Json>, i: Int64) -> Json
Element i, or JNull when the index is past the end.
fn tagOf(v: Json) -> String
A bare string's content (a nullary enum variant's wire form), or "". No variant can be named "", so the sentinel cannot collide with a real tag.
fn pushType(iss: modify Array<Issue>, path: String, expected: String, found: String) -> Unit
json.type: expected <what>, found <kind>.
fn pushMissing(iss: modify Array<Issue>, path: String, field: String) -> Unit
json.missing: missing required field `name`.
fn pushValidate(iss: modify Array<Issue>, path: String, message: String) -> Unit
validate: a refined type's where clause did not hold. The caller passes the compiler's validation message, so the trap and this path word it the same.
fn fieldPath(parent: String, field: String) -> String
A dotted path extended by a record field (or an enum tag).
fn indexPath(parent: String, i: Int64) -> String
A path extended by an array index.
fn pathAt(path: String, seg: String, idx: Int64) -> String
The path of a value a decoder reads: path itself when idx is -2, path[idx] for an element, and path.seg for a member when idx is -1. A decoder builds it only for an Issue or for its own members, so a value that decodes builds no path.
fn openDoc(src: String) -> JsonReader
A reader over src.
fn closeDoc(p: modify JsonReader) -> Array<Issue>
Ends a decode: [], or the one json.parse Issue of a refused document.
fn kindAt(p: JsonReader) -> Int64
The kind of the value at the cursor, as std/jsonread's kindAt names it.
fn kindName(k: Int64) -> String
fn expect( p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>, kind: Int64, what: String, ) -> Bool
Whether the value at the cursor is of kind, a kindAt kind. If it is not, records expected <what>, found <kind> at the value's path (see pathAt) and reads the value past.
fn readNull(p: modify JsonReader) -> Bool
Reads a null at the cursor and answers whether there was one: the wire form of an absent Option.
fn readString(p: modify JsonReader) -> String
fn skipValue(p: modify JsonReader) -> Unit
fn enterObject(p: modify JsonReader) -> Bool
fn enterArray(p: modify JsonReader) -> Bool
fn readKey(p: modify JsonReader) -> String
fn keyIs(p: modify JsonReader, name: String) -> Bool
fn nextMember(p: modify JsonReader) -> Bool
fn nextItem(p: modify JsonReader) -> Bool
fn keySet() -> JsonKeySet
fn member(p: modify JsonReader, seen: Bool, key: String) -> Unit
Reads past the : after a record member's key, or refuses the key as a duplicate when the member was seen.
fn mapMember(p: modify JsonReader, keys: modify JsonKeySet, key: String) -> Bool
Records key in keys and reads past the :, answering true; or refuses the key as a duplicate and answers false.
fn skipMember(p: modify JsonReader, keys: modify JsonKeySet, key: String) -> Unit
Reads a member no field claims: an unknown field is ignored, but its key may not repeat and its value must be JSON.
fn takeIssues(iss: modify Array<Issue>, base: Int64) -> Array<Issue>
Moves iss[base..] out, in order: a record puts its members' Issues back in declaration order with putIssues.
fn putIssues(iss: modify Array<Issue>, late: Array<Issue>, a: Int64, b: Int64) -> Unit
Appends late[a..b], end excluded, to iss.
fn dStr(p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>) -> Array<String>
fn dBool(p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>) -> Array<Bool>
fn dInt64(p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>) -> Array<Int64>
A JSON integer-syntax number as an exact Int64. A fraction, an exponent or a magnitude outside Int64 is expected integer, never a rounded value.
fn dIntKey(key: String, path: String, iss: modify Array<Issue>) -> Array<Int64>
An object key read as an Int64, the wire form of Map<Int64, V>, in the map at path. Only the canonical text (n.toString()) passes: "007" and "+7" would otherwise collapse into the key "7" with no Issue.
fn dIntRange( p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>, lo: Int64, hi: Int64, ) -> Array<Int64>
dInt64 restricted to [lo, hi], for the sized signed integers.
fn dUIntMax( p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>, hi: UInt64, ) -> Array<UInt64>
A JSON integer-syntax number as an exact UInt64 in [0, hi]. parseInt64 cannot serve: it has no room above Int64.max.
fn dFloat64(p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>) -> Array<Float64>
A JSON number as a Float64, correctly rounded (std/num). Integer syntax is accepted: 1 decodes into a Float64 target as 1.0.
fn dFloat32(p: modify JsonReader, path: String, seg: String, idx: Int64, iss: modify Array<Issue>) -> Array<Float32>
A JSON number as a Float32, rounded once: decimal -> Float64 -> Float32 rounds twice and is wrong near a Float32 tie.
gen fn jsonDecoders(t: TypeArg) -> String
Writes the decoders fromJson calls: for each root, the entry that reads a document into Validation<T>, and for each node, the function that decodes the value at a reader's cursor into zero or one value. Generated source cannot spell reserved names, so it writes VyrnRt_ for std/json's, VyrnRd_ for this module's and VyrnWp_ for a where type's predicate.
Tests
7 test blocks in std/jsondec.vyrn. CI runs all of them.
Test names
- a decode result is zero or one element
- integers decode exactly, never through a Float64
- a sized integer out of range is a type issue, not a wrap
- a wrong kind is a type issue, and the value is read past
- paths compose the canonical way
- a parse error is one issue, keyed json.parse, worded line/col
- a string's content is its tag
Examples
1 program in examples/ import this module. Each runs as WebAssembly and as a native binary.