# Changelog All notable changes to **interpres** are documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). ## [development] ### Added - `encoding.TextMarshaler` and `encoding.TextUnmarshaler` are honoured by default, with no option to switch them off. A type that implements them is encoded as a TOML string and decoded from one: `net.IP` becomes `"192.0.2.1"`, and a user type with `MarshalText` or `UnmarshalText` follows. `MarshalTOML` and `UnmarshalTOML` still win over the text methods, and the four date-time types keep their bare timestamp form instead of becoming a quoted string. A struct type that implements the interface now encodes as a string where it was a table before, which is the breaking part of the change. - `time.Duration` is encoded in its canonical Go form as a TOML string, `1h30m0s`, because TOML has no duration type; the decoder reads that string back and still accepts a bare integer as the nanosecond count. - `interpres-decode -encode`, the adapter's other direction: it reads the toml-test tagged JSON from stdin and writes the TOML document it describes. The compliance suite now runs the encoder as well as the decoder, 214 encoder cases against the tagged JSON of the valid corpus. - `Encoder.InlineTables(threshold)`: a sub-table whose single-line rendering is at most `threshold` bytes is written as an inline table instead of a header section, which shortens a document of small tables. An array of tables keeps its header form, because its inline form would re-parse as a value array. - `Document` and `ParseMap`: `Parse` now returns a `*Document`, which holds the values together with the key order, whether a table was written as an inline table or under a header, and the comments, with `Keys`, `Entries`, `Get`, `Comments` and `SetComments` to read and write them. `ParseMap` returns the plain `map[string]any` tree, the shape `Parse` used to give. `Marshal` does not accept a `Document`; it writes values, so `doc.Map()` is the way through. - `OffsetDateTime`, the Go type of the offset date-time kind, so that all four TOML date-time kinds have one of their own. `Parse` and `Unmarshal` hand it back where they produced a bare `time.Time` before, and `Marshal` accepts it. Unmarshalling into a struct field of type `time.Time` keeps working, because the plain type takes an offset date-time as it always did; code that asserts the tree's type, and `UnmarshalTOML` implementations that expect a `time.Time`, need the new type. - `Decoder.MaxDepth(depth)` and `Decoder.MaxInputSize(size)` bound the parse a `Decode` performs, and every parse carries a nesting limit in any case (10000 levels, which no hand-written document approaches): a document that nests arrays or inline tables deeper used to run the stack out and is now rejected with a `SyntaxError` naming the limit. ### Changed - The output takes the TOML 1.1 form. A date-time writes its seconds only when the value carries them and drops the trailing zeros of a fractional second, so `07:32:00` is written `07:32` and half a second as `00.5`. Both are the same value, and a document written without seconds now comes back without them. `LocalDateTime.String()`, `LocalTime.String()` and the offset date-time rendering follow the same rule. - An inline table that would pass the hundredth column is written across lines with a trailing comma and one tab of indentation per nesting level, the shape TOML 1.1 allows an inline table to take. - `MarshalTOML` reaches every array element and every field, whatever the Go kind, and its result is normalised like any other value: an element rendering itself as a table keeps the `[[header]]` form, one rendering itself as a scalar turns the array into a value array, and the method runs once per element. It is found on the addressable pointer as well, so a pointer-receiver `MarshalTOML` is called for a field or an element, exactly as `MarshalText` is. - TOML 1.1 is the acceptance contract, and TOML 1.0 is not. The compliance suite runs the 1.1 corpus alone, and the promise that every 1.0 document parses exactly as before is withdrawn. Nothing that parses today stops parsing: the 1.0 valid corpus still passes in full. The documents whose verdict changes are the ones 1.1 relaxed, such as the `\xHH` escape sequences 1.0 rejected. - The module path carries the /v2 suffix the Go toolchain requires of every major version 2 module: imports change to `sourcedock.dev/petrbalvin/interpres/v2`. - Input that is not valid UTF-8 is now rejected where the parser's scan meets the invalid byte, with a `SyntaxError` naming that line, instead of a whole-input check that always reported line 1. Invalid input is still rejected; the reported location is now the byte's own. **Performance** - Parsing is faster than in 1.1.0 while carrying the new document layer: the suite's representative document decodes at about 79 MB/s with 104 allocations per call, and the long array-of-tables document at about 106 MB/s against 56 MB/s in 1.1.0, with allocations on that document halved from 67 664 to 31 765. Date-time tokens are validated by a byte scan instead of regular expressions, repeated keys share one string across array-of-tables elements, and per-statement buffers are reused. - Typed decoding is 12 percent faster than in 1.1.0 on the representative document (9792 ns against 11 147 ns) with 24 percent fewer allocations (167 against 220); interface lookups resolve through a cached per-type flag set instead of boxing every value into an interface to ask. ### Fixed - Decoding into a defined type whose underlying kind is string or bool, such as `type Name string`, panicked instead of storing the value, because a value of the predeclared type is not assignable to a defined type and the decoder assigned it without a conversion. ## [1.1.0] - 2026-09-18 ### Added - TOML 1.1 support, on by default: date-times and times without seconds (`07:32`, `1979-05-27T07:32`, normalised to full seconds on output), the `\e` and `\xHH` escape sequences, and multi-line inline tables with comments and trailing commas. The compliance suite runs in TOML 1.1 mode: 214 valid and 467 invalid cases, zero failures. Every TOML 1.0 document parses exactly as before. - `interpres-decode -validate [file ...]`: a validate mode beside the toml-test adapter. It parses each named file, or stdin when none are named, prints one line per invalid document to stderr, and exits 0 when all are valid, 1 when one is not, and 2 on a usage or read failure. Install it with `go install .../cmd/interpres-decode@latest`; releases still ship no binaries. - `DecodeError` and `EncodeError`: decode and encode failures are wrapped in typed errors carrying the key path, read with `errors.AsType` instead of parsing the message text. The rendered messages keep their shape; the only visible change is that an encode failure on a top-level field no longer gains a meaningless leading dot in its path. - `omitzero` and `omitempty` tag options on encode: `toml:"name,omitzero"` skips a field whose value is the zero value of its type (a type with an `IsZero() bool` method decides through the method), and `toml:"name,omitempty"` skips a nil or empty slice, array, or map. The decoder ignores both options. ### Changed - The compliance suite is [toml-test](https://github.com/toml-lang/toml-test) v2.2.0, up from v1.6.0. Its TOML 1.0 corpus holds 205 valid and 474 invalid cases (185 and 371 before), and it caught the two documents the parser still accepted, fixed below. - The flattened struct layout the decoder consults is cached per struct type and shared with the encoder, which now resolves duplicate field keys with it. Strict decoding of an array of tables of structs runs about a quarter faster; marshalling structs gained the same layout without measurable cost. - The parser scans the input bytes in place instead of building a `[]rune` copy of the document: every character that drives the grammar is ASCII and the input is validated UTF-8 up front, so the conversion pass and its four bytes per rune were pure overhead. Parsing a large array-of-tables document runs about a fifth faster and allocates about half the memory. - Numeric tokens without underscores skip the normalising rebuild: digits are validated in place in `joinDigits`, and a float whose token is already clean goes to `strconv.ParseFloat` directly. One allocation per integer atom and two per float atom disappear. ### Fixed - A `MarshalTOML` result of `nil` with a nil error fails the marshal with `MarshalTOML returned a nil value`. The field silently vanished before, and inside a value array the nil result reached reflection as a zero value and panicked. - Strict decoding reports the smallest unknown key. Several unknown keys in one table made the message depend on Go's random map iteration order, so the same document reported different keys across runs. - Decoding into a struct that embeds a pointer to itself terminates. The schema walk recursed through the embedded type forever, so such a `Unmarshal` call hung the process; the walk now tracks the struct types on the current path and stops when one repeats. - An array-of-tables header whose path runs through an inline table (`a = {b = {}}` followed by `[[a.b.c]]`) is rejected. The frozen-inline-table check covered `[table]` headers and dotted keys but not the intermediate steps of an array-of-tables header, so such a document silently extended the inline table. - A new element of an array of tables starts a fresh scope for dotted-key paths and nested arrays of tables: `[[a]]`, `b.c = 1`, `[[a]]`, `[a.b]` parses, as the TOML examples in the spec shape it. The records of the previous element falsely rejected the same paths in the next one. - `Marshal` emits exactly one key when two struct fields resolve to the same TOML name, picking the field the decoder would fill (the shallower one, the later declaration at equal depth). Such a struct previously marshalled into a duplicate key, and the output never re-parsed, breaking the round-trip guarantee. - `Marshal` returns an error for a table header key or an inline-table key that is not valid UTF-8, the way scalar keys already did, instead of silently emitting corrupt TOML (a header that lost its key, an inline table with a missing key). - `UseLiteralMultiline` falls back to the escaped basic string when the value cannot be carried verbatim by the literal form: a run of three single quotes, a control character, or a lone carriage return. Such values previously produced output that did not re-parse. - A `[]any` holding only tables marshals in the value-array form with inline tables, keeping the type `Parse` produces for such an array. It previously took the `[[header]]` form, so a round-trip changed the value's type from `[]any` to `[]map[string]any`. - Decoding into a `uint` destination checks the type's platform width instead of only the fixed widths, so a 32-bit `uint` no longer truncates silently; decoding a finite float beyond the `float32` range is an overflow error instead of a silent infinity. - Struct fields that resolve to one key at equal depth decode through the field declared later, matching the documented rule; the first one won before. - A float with an exponent marker but no digits (`1e`, `0.0E`) is rejected; the exponent requires at least one digit. - A date-time offset outside 00:00 through 23:59 is rejected; such offsets were accepted and silently rolled over (`+00:60` decoded as `+01:00`). - Untagged embedded fields now decode symmetrically with encode: an embedded struct receives its keys inline (a nil embedded pointer struct is allocated), an embedded map catches the keys no field claims, and a name clash resolves in favour of the shallower field. A struct with an untagged embedded field previously decoded with all inline keys dropped and did not round-trip. - `Marshal` re-emits arrays that mix tables with scalars: the table elements render as inline tables inside the value array. A tree that `Parse` accepts from such a document previously failed with `cannot encode map[string]interface {}`. ## [1.0.0] - 2026-08-20 First stable release: a dependency-free TOML 1.0 parser and encoder for Go that uses only the standard library and passes the entire [toml-test](https://github.com/toml-lang/toml-test) suite (**185 valid and 371 invalid cases, 0 failures**). ### Added **Parsing** - `Parse(data []byte) (map[string]any, error)`: decode a TOML document into an untyped tree. - Full TOML 1.0 syntax: comments; bare, quoted, and dotted keys; tables (`[a.b]`) and arrays of tables (`[[a]]`); basic and literal strings, including multiline (`"""` / `'''`) with escape sequences and line-ending backslash trimming; integers in decimal, hex (`0x`), octal (`0o`), and binary (`0b`) with `_` separators; floats with exponents and `inf` / `nan`; booleans; offset/local date-times, dates, and times; arrays; and inline tables. - Distinct date-time types: offset date-times decode to `time.Time`, while `LocalDateTime`, `LocalDate`, and `LocalTime` represent the local variants, each with a `String()` method returning the TOML-canonical rendering. - Strict, spec-conformant validation that rejects invalid documents: leading zeros, misplaced underscores, malformed floats and radix literals, control characters in strings and comments, bare carriage returns, non-UTF-8 input, out-of-range Unicode escapes, multiline strings used as keys, single-digit date-time components, duplicate/overwriting inline-table keys, and the full family of table redefinitions (header vs. header, header vs. dotted key, array of tables vs. table, and dotted-key appends to defined tables). - `SyntaxError` carrying the 1-based line of a malformed document. **Decoding** - `Unmarshal(data []byte, v any)`: parse and map onto a struct or `map[string]any` via reflection, with overflow-checked numeric conversion, nested structs, slices, and `map[string]T`. - `toml:"name"` field tags, case-insensitive name fallback, and `toml:"-"` to skip a field. - `Decoder` with `DisallowUnknownFields` for strict decoding that rejects keys without a destination field, at every struct depth. - `Unmarshaler` interface (`UnmarshalTOML(data any) error`) for types that take full control of their decode. **Encoding** - `Marshal(v any) ([]byte, error)`: encode a struct or `map[string]V` value to a TOML 1.0 document that re-parses to an equivalent value tree. - `Encoder` with chainable policy options: `GroupByKind` (group-by-kind layout versus declaration order), `OmitEmptyArrays`, and `UseLiteralMultiline`. - `Marshaler` interface (`MarshalTOML() (any, error)`) for types that need a custom TOML shape; the returned value is encoded normally. **Cancellation** - `ParseContext`, `UnmarshalContext`, `MarshalContext`, `(*Decoder).DecodeContext` and `(*Encoder).MarshalContext` honour a `context.Context`, checked up front and every 64 statements or fields. **Project** - Standard library only: zero third-party modules. - `cmd/interpres-decode`, a toml-test harness adapter (TOML on stdin, tagged JSON on stdout). - A runnable example, a table-driven Go test suite, and a canonical `just` recipe set whose `gates` recipe is the definition of done. - Hand-written CI pipelines for the test, race and release gates. - `SECURITY.md` for private vulnerability reports.