icarus

func ApplyRowPatch ¶

func ApplyRowPatch(baseJSON []byte, row ExmodRow) ([]byte, error)

ApplyRowPatch applies row's File_Items to baseJSON, a real Icarus DataTable JSON export — the standard Unreal Engine shape {"RowStruct": "...", "Defaults": {...}, "Rows": [{"Name": "...", ...fields}, ...]}, confirmed against a real installed data.pak (task-7-report.md); not the flat {name: {fields}} map this function originally assumed, which never matched real game data and was only ever exercised against synthetic fixtures.

Each File_Item is an upsert, not a strict patch: if its Name matches an existing entry in Rows, that row's fields are shallow-merged with the item's fields (item fields win, everything else on the row survives untouched); if no row has that Name, the item is appended to Rows verbatim as a brand-new row. This matches what real .EXMOD content actually does — most rows patch existing base stats, but a content-adding mod (e.g. a new mountable species) introduces rows the base game doesn't have yet, and erroring on that (the original patch-only design) made every such mod uncompilable. All other top-level keys on the base document (RowStruct, Defaults, and anything else) pass through re-serialization unchanged, since only doc["Rows"] is ever modified. Output is deterministic: encoding/json sorts map keys.

func Compile ¶

func Compile(basePakPath, exmodzPath, outputPakPath string) (err error)

Compile reads exmodzPath's .EXMOD diff, applies it to the game's base data tables, bundles in any pre-built assets the .EXMODZ carries, and writes the result as a new pak at outputPakPath ready to deploy as-is.

Base tables are read directly out of basePakPath — the installed game's own Content/Data/data.pak — so they are always week-correct by construction and the whole operation is offline. That pak stores 40 tables uncompressed and compresses the other 258 with Zlib, all of which go-unrealpak reads with the standard library (#175). basePakPath is also what resolves a bare, hyphen-flattened CurrentFile to a real mount path.

There is no ctx parameter: every step is local file I/O over a ~2 MB pak, with no network call and no long-running loop to cancel. The source.MergeCompiler interface still takes one, for implementations that need it (MergeCompile, this package's own N-mod entry point, is one).

The compiled pak's mount point and table-entry paths (icarusContentMountPoint, icarusDataTablePrefix below) are Icarus-specific and deliberately live here rather than in go-unrealpak, which stays game-agnostic — see unrealpak.Writer's WithMountPoint. They are not guessed: both were confirmed against two real, working prebuilt Icarus mod paks (#178; see docs/plans/2026-08-01-icarus-zlib-pivot.md's pak-divergence-report.md).

func MergeCompile ¶

func MergeCompile(ctx context.Context, basePakPath string, sources []MergeSource, outputPakPath string) (warnings []string, failed []source.MergeFailure, err error)

MergeCompile applies every source's .EXMOD row upserts, IN ORDER, against the same evolving base tables - a merge is just Compile with N diffs instead of 1. Table conflicts compose at the FIELD level for free: ApplyRowPatch always shallow-merges an item's fields into whatever the target row currently holds, so feeding mod A's patched bytes back in as the "base" for mod B's row (instead of re-reading the pristine base table each time) is the entire merge algorithm - two mods patching DIFFERENT fields of the same row, or entirely different rows of the same table, both survive; only a genuine same-row-same-field write is last-wins (an ordinary, expected upsert outcome, not something to warn about). Bundled ASSET files cannot compose this way - a same-path asset collision is necessarily last-wins, so it is reported as a warning instead.

ctx is accepted only to satisfy source.MergeCompiler and is never read - every step here is local file I/O over small files (mirrors Compile's own doc comment, internal/source/icarus/compile.go:23-25).

A non-nil error always means outputPakPath does not exist (or does not contain a fully-written pak) - see the removal defer below, mirroring Compile's own fail-clean contract.

func ValidateSource ¶

func ValidateSource(sourceFilePath string) error

ValidateSource parses sourceFilePath without compiling anything - the ingest-time check. .exmodz archives fully parse (#197); .pak files (#221) open + enumerate only - full conversion is checked at merge time BY DESIGN (the result depends on the current base pak, which changes weekly).