interpres/CHANGELOG.md

Changelog

All notable changes to interpres are documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[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.

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.
• 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 The compliance suite runs the 1.1 corpus alone, and the promise that every 1.0 document parses exactly as before is withdrawn.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.

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 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 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.