Third-party source and reference inventory
==========================================

This package remains licensed under GPL-3. The following incorporated portions
are also subject to the preserved upstream notices below.

Adapted from dplyr 1.2.1:
  Revision: 95740975c465c29cdb2abdfa13effddb948444dc
  Source: https://github.com/tidyverse/dplyr/tree/95740975c465c29cdb2abdfa13effddb948444dc
  R/select.R: select.data.frame(), ensure_group_vars()
  R/rename.R: rename.data.frame()
  R/relocate.R: relocate.data.frame(), eval_relocate()
  R/grouped-df.R: [.grouped_df and names<-.grouped_df policies
  R/rowwise.R: [.rowwise_df and names<-.rowwise_df policies
  Destinations: R/dibble-result.R and the select, rename, and relocate methods
    in R/mutate-data.R.
  Changes: package-owned column-list assembly and result finalization replace
    whole-table dplyr dispatch. Existing dibble typing, metadata, isolation and
    capacity rules apply. Selector helpers use qualified public tidyselect,
    rlang and base R functions. Group retention and renaming are explicit.
  Tests: public selector cases adapted into tests/testthat/test-dibble-columns.R
    from tests/testthat/test-select.R, test-rename.R and test-relocate.R,
    with Stata-typed fixtures and additional dibble ownership assertions.
  Additional Stage 2 sources:
    R/grouped-df.R: compute_groups(), dplyr_locate_sorted_groups(),
      group_data_trim(), group_intersect(), [.grouped_df
    R/rowwise.R: rowwise_df(), new_rowwise_df(), [.rowwise_df
    R/generics.R: grouped/rowwise dplyr_row_slice() and dplyr_reconstruct()
    R/arrange.R: dplyr_order_legacy(), dplyr_proxy_order_legacy()
    R/locale.R: dplyr_legacy_locale() option validation
    src/group_by.cpp: FactorExpander, VectorExpander, LeafExpander and
      grouping validation policies
  Additional destinations: R/dibble-groups.R, R/dibble-rows.R and the
    row/reconstruction hooks in R/mutate-data.R.
  Changes: factor expansion is expressed as R recursion over integer key
    positions; public vctrs grouping/slicing and tibble construction replace
    dplyr internals. Validation additionally requires a complete partition and
    matching keys before expressions run. Partition counts are linear, and
    compatible equality proxies are expanded after casting observed keys.
    Stage 7 reduces temporary allocations for ordinary integer partitions and
    uses public character match codes for classless ordinary or known-owned
    character keys. Custom classes, foreign storage and inputs with a non-NULL
    stata.storage attribute retain the general path and per-key error order.
    These are package-specific validation changes; nested capture and
    mutable-metadata checks remain.
    These use public vctrs APIs; no additional upstream source is incorporated.
    Native gathering uses the existing
    dtatools kernel. Missing strings are normalized before groups are rebuilt;
    arbitrary dataset metadata survives grouped reconstruction. The grouped
    row hook preserves its separate existing-group remapping policy. The
    legacy locale option uses base ordering of public vctrs proxies. Stage 6
    additionally adapts its lifecycle deprecation policy for arrange().
  Additional tests: tests/testthat/test-dibble-rows.R adapts group expansion,
    rowwise identifier and reconstruction cases from test-group-by.R,
    test-grouped-df.R, test-generics.R and test-rowwise.R, with package-specific
    storage, metadata, indexing and later-write isolation assertions.
    test-dibble-group-validation.R adds package-specific character equality,
    source state, foreign-length fallback and allocation regressions.
  Additional Stage 5 sources:
    R/context.R: context_env, public context helpers and restoration contract
    R/conditions.R: warning record fields and signal_warnings integration
    R/data-mask.R: DataMask helper methods, fresh lexical masks, used columns,
      rowwise extraction and obsolete-mask lifetime
    R/mutate.R: mutate_cols, mutate_col, mutate_keep and mutate_relocate policies
    R/transmute.R: transmute.data.frame and check_transmute_args policies
    R/by.R: compute_by and compute_by_groups ordering policies
    R/group-by.R: group_by_prepare, add_computed_columns,
      ungroup.grouped_df, ungroup.rowwise_df and ungroup.data.frame policies
    R/rowwise.R: rowwise.data.frame and rowwise.grouped_df
    src/chop.cpp: zero-row list/list-of prototype rule
  Destinations: R/dibble-expressions.R, R/dibble-dplyr-context.R and the
    mutate/transmute/group_by/rowwise/ungroup methods in R/mutate-data.R.
  Changes: one package-owned R evaluator replaces dplyr whole-verb evaluation.
    Column generations use isolated public handles and fixed-group bindings,
    with call-local invalidation of deferred reads. Public vctrs operations
    perform recycling and chunk assembly. Stata typing and conservative capture
    precede dependent expressions. Group metadata uses the existing module.
    Private context_env, expand_pick, expand_across and signal_warnings calls are confined to
    the optional adapter; their function bodies are not copied or patched.
    Expanded selections use full current columns; public fallback helpers use
    real dplyr against the current group. Minimum supported dplyr is 1.2.1.
  Additional tests: tests/testthat/test-dibble-expressions.R adapts helper,
    empty-group, capture and expansion cases from test-mutate.R, test-across.R,
    test-pick.R, test-group-by.R and test-rowwise.R and the standalone Stage 5
    helper proof, adding Stata sequencing and symmetric write-isolation checks.
  Additional Stage 6 sources:
    R/filter.R: filter.data.frame, check_filter, filter_rows, filter_expand
      and filter_eval policies
    R/across.R: expand_if_across integration contract
    src/filter.cpp: TRUE-only conjunction, predicate size/type validation and
      inversion after all predicates have been evaluated
    R/arrange.R: arrange.data.frame, arrange_rows, legacy proxy ordering,
      locale validation and collation
    R/locale.R: legacy-option validation and notification
    R/distinct.R: distinct.data.frame and distinct_prepare
    R/slice.R: slice.data.frame, slice_rows, slice_eval, slice_combine,
      get_slice_size, slice_rank_idx and head/tail/min/max/sample policies
  Destinations: R/dibble-row-operations.R, src/row-filter.h, shared evaluator/context/group
    interfaces and row-operation methods in R/mutate-data.R.
  Changes: shared group-local evaluation plans row locations, then the existing
    package row gatherer restores typed columns, metadata and ownership.
    Arrange uses public vctrs ranks to obtain stable row permutations instead
    of private vctrs ordering. Distinct uses the shared sequential typing
    evaluator. Filter helper expansion is confined to the optional adapter;
    no installed namespace functions are patched. R evaluates and validates
    every filter predicate; an R-managed private byte buffer in C accumulates
    TRUE-only results and emits physical row locations after final inversion.
    An explicitly ungrouped plan reduces contiguous rows without materializing
    group indices; indexed groups retain row validation. The finish pass caches
    its rooted ordinary result pointer. These are package-specific changes.
    Public lifecycle and optional stringi APIs provide the
    adapted deprecation and explicit-locale policies.
  Additional tests: tests/testthat/test-dibble-row-filter.R,
    test-dibble-row-order.R, test-dibble-row-slice.R and
    test-dibble-row-lifetime.R adapt test-filter.R, test-arrange.R,
    test-distinct.R and test-slice.R. They use typed dibbles, stable row IDs,
    explicit Stata metadata and symmetric mutation checks. The retained
    Stage 6 caller witnesses additionally informed group-frame and empty-group
    cases. Preparation drafts and their failed expectations are not package
    qualification; the integrated tests are checked on the installed source.
  Additional Stage 7 sources:
    R/summarise.R: summarise_cols, summarise_eval_one, summarise_build,
      summarise.data.frame/grouped_df/rowwise_df and grouping messages
    R/reframe.R: reframe.data.frame
    src/summarise.cpp: deferred size-one checking and horizontal recycling
    R/data-mask.R: summary chunks, rowwise scalar-list binding and context reset
    R/vctrs.R, R/conditions.R, R/context.R: common-type error classes and
      named-group details, adapted to the owned group plan and public formatting
    R/pick.R: expand_pick integration contract
    R/group-map.R: as_group_map_function and group_modify methods
    R/group-split.R: group_split_impl and group prototypes
    R/group-nest.R and R/nest-by.R: grouping, nesting and key policies
  Destinations: R/dibble-summaries.R, R/dibble-callbacks.R, the optional
    context adapter and five methods in R/mutate-data.R.
  Changes: explicit per-group chunks retain immediate Stata typing before
    common casting and dependent dots; summary sizes are checked after all
    dots, while reframe recycles horizontally. The first assembled result is
    reused only when all recorded chunk sizes match the final group sizes;
    otherwise the existing recycling and assembly path remains.
    Typed across callbacks retain
    the observed predecessor group-major order. Public vctrs assembly and
    package gathering/finalization replace whole-verb dplyr delegation.
    Shared R/dibble-nested-capture.R is package-specific storage capture for
    nested frame/list publication, preserving public classes and intentional
    reference-valued objects rather than assuming a shallow list is isolated.
    A call-local active-node guard rejects cyclic nested list/frame payloads
    before vector assembly; completed acyclic siblings can reuse their capture.
    Its memo uses the public utils address-hash API with actual object keys and
    fixed-field source/result entries, avoiding per-address environment binding
    names. Each sibling list computes its first-identity index once.
  Additional tests: test-dibble-summary.R and test-dibble-callbacks.R adapt
    test-summarise.R, test-reframe.R, test-across.R, test-pick.R,
    test-group-map.R, test-group-nest.R and test-nest-by.R policies, with typed
    predecessor oracles and package-specific isolation/metadata regressions.
  Additional Stage 8 join sources:
    R/join-cols.R: join_cols, join key/name/suffix checks, add_suffixes,
      common key casting and incompatible-type attribution
    R/conditions.R: err_vars formatting of problematic names/positions
    R/join-rows.R: join_rows, match missing/unmatched/relationship policies,
      direct-caller warning eligibility and match-condition translation
    R/join-by.R: as_join_by character/list/specification normalization,
      natural key selection
    R/join.R: seven public method argument policies, empty-key cross-join
      compatibility, join_mutate,
      join_filter and nest_join.data.frame assembly/coalescing policies
    R/join-cross.R: cross_join.data.frame naming and replication policy
  Destinations: R/dibble-join-plan.R, R/dibble-join-matches.R and
    R/dibble-joins.R, registered through the dtatools_ref_data methods.
  Changes: package-owned key/name planning, public vctrs match locations,
    batched column gathering and shared owned result finalization replace
    whole-table join dispatch for dibbles. Ordinary reference frames retain
    their existing next-method route. Stata-specific dta_merge policies remain
    separate. Error wording uses base formatting, preserving match-condition
    classes and side/row attribution. Public as_tibble conversion, auto_copy and reconstruction
    remain extension boundaries for non-dibble inputs and nested templates.
  Tests: the initial Stage 8 equality/inequality, mixed-container, missing-code,
    condition and nested/grouped observation fixtures are newly authored after
    studying test-join.R, test-join-cols.R, test-join-rows.R and test-join-cross.R.
    Installed regressions in tests/testthat/test-dibble-joins.R retain explicit
    row-map and missing-payload assertions, public extension/forcing contracts,
    ordinary-reference dispatch and isolated nested-write checks.
  Additional Stage 8 binding and reconstruction sources:
    R/rows.R: rows_insert/append/update/patch/upsert/delete.data.frame,
      rows_check_by, rows_check_x_contains_y, key checks, rows_check_unique,
      conflict/unmatched filtering and rows_bind policies
    R/generics.R: dplyr_col_modify.data.frame/grouped_df/rowwise_df
    R/grouped-df.R: grouped_df, compute_groups, dplyr_regroup condition
    R/rowwise.R: rowwise_df and new_rowwise_df identifier policies
  Destinations: R/dibble-rows-mutate.R, R/dibble-column-modify.R and the
    opt-in regroup signal in the shared R/dibble-groups.R builder.
  Changes: package-owned rows orchestration resolves key and payload casts
    separately, applies conflict/unmatched/missing rules, assigns matched
    values and uses public table extension points. Public vec_rbind and
    dplyr_reconstruct retain append-tail prototype/restore behavior; public
    coalesce retains vector missing-value semantics for rows_patch. They are
    dependencies, not incorporated implementations. Column modification owns
    standard recycling/list assembly and group reconstruction while retaining
    separate public custom modification and reconstruction dispatch. Existing
    Stata typing and shared publication capture every result. These modules
    do not delegate an entire rows verb on the dibble path.
  Tests: tests/testthat/test-dibble-bindings.R adds concrete rows, storage,
    grouped reconstruction, base-binding and foreign-write regressions after
    studying the pinned rows/generics policies and retained predecessor results.
  Package-specific Stage 8 finalizer changes remove unused column-context
    lineage bindings for the current sources=NULL callers, reuse an already
    prepared repeated slot, and key constructor/reserve caches by the actual
    normalized or current physical object. Public utils address hashes replace
    per-address environment names. Atomic nested capture performs its existing
    metadata copy before any list memo is allocated. No additional R or utils
    implementation is incorporated by these changes.
    tests/testthat/test-dibble-result-history.R adds package-specific finite
    retained-heap budgets and atomic-copy/opaque-identity assertions.
  Additional Stage 9 display sources:
    R/grouped-df.R: group_sum and tbl_sum.grouped_df
    R/rowwise.R: tbl_sum.rowwise_df
    R/utils-format.R: big_mark
    R/utils.R: commas
  Destination: the grouped/rowwise metadata fallback in R/print-dibble.R.
  Changes: preserve existing registered table summaries and supply only a
    missing Groups or Rowwise header from the stored grouping metadata.
    No optional namespace is loaded to format the header.
  Additional Stage 9 replacement sources:
    R/grouped-df.R: [<-.grouped_df, [[<-.grouped_df and names<-.grouped_df
    R/rowwise.R: [<-.rowwise_df and names<-.rowwise_df
  Destinations: replacement finalization in R/mutate-data.R and method
    availability checks in R/dibble-groups.R.
  Changes: when a standard grouping method is absent, validate the original,
    normalize an ungrouped intermediate, and rebuild its groups through the
    shared package module. Rowwise [<- instead captures its observable raw
    key metadata before column promotion, retaining final validation.
    Renaming preserves the original partition. Visible
    or registered grouping methods retain their existing dispatch path.
  Additional recoding sources:
    R/recode.R: recode.character(), recode.factor(), find_template(),
      validate_recode_default(), recode_default.default(),
      recode_default.factor(), replace_with() and replacement checks.
    R/error.R: bounded positional-argument formatting.
  Destination: owned character/factor kernels and helpers in R/recode.R.
  Changes: qualified public rlang/base calls replace dplyr helper access;
    replacement type errors use the package's typeof wording. The private
    dispatcher uses public S3 lookup and base dispatch for owned core methods.
    A separate optional adapter calls the public generic only for a selected
    foreign method, preserving its dispatch environment and dynamic NextMethod
    behavior. Numeric Stata and legacy kernels remain
    distinct. Character-backed Haven inputs extract their underlying character
    data through public vctrs APIs and use the owned character kernel,
    avoiding the former public-wrapper/generic recursion. Metadata wrappers
    retain their existing separate restoration policy. No dplyr generic or
    recode_factor implementation is incorporated.
  Additional tests: tests/testthat/test-recode-core.R adapts named replacement,
    default/missing, dynamic dots, factor-level order/collapse and validation
    cases from tests/testthat/test-recode.R. Additional package-specific tests
    cover metadata, missing tags, forcing and external S3 continuation; no
    upstream snapshots or numeric tests were copied.
  Package-specific optional registration in R/dplyr-registration.R uses public
    base registration and package-event APIs. It retains prior method ownership,
    removes its own hooks on unload and leaves unrelated replacements intact.
    R 4.6.1 src/library/base/R/namespace.R was studied to identify retained
    delayed hooks and registration metadata; no implementation was copied.
    tests/testthat/test-dplyr-optional.R adds namespace, reload, restoration,
    registration rollback and native no-load checks.
  The inspected files contain no separate file-level copyright or license.

Adapted from R 4.6.1, released 2026-06-24 (SVN revision 90187):
  Source: https://svn.r-project.org/R/tags/R-4-6-1/src/library/base/R/dataframe.R
  Function: [.data.frame
  File attribution: Statlib code by John Chambers, Bell Labs, 1994.
    Changes Copyright (C) 1998-2025 The R Core Team.
  License: GPL version 2 or, at your option, any later version. These adapted
    portions are incorporated under this package's GPL-3 license. The upstream
    COPYING text is reproduced below, including its warranty disclaimer.
  Destination: R/dibble-rows.R, .reference_base_rows(), modified 2026-09-06.
  Changes: preserve base subscript evaluation, drop, names and attribute rules
    while planning rows on a single integer column and gathering payloads in
    batches. Package-owned reference and Stata metadata restoration apply.
  Tests: package-specific cases in tests/testthat/test-dibble-rows.R compare
    these rules against the public base method. No base R tests were copied.
  Additional Stage 8 functions from the same dataframe.R revision:
    data.frame, rbind.data.frame and cbind.data.frame.
  Destinations: R/dibble-base-bind-construction.R (.dibble_base_data_frame,
    .dibble_base_rbind), and R/dibble-base-bind.R (.dibble_base_cbind and
    the reference-frame base binding methods), modified 2026-09-09.
  Changes: the complete standard data.frame and rbind.data.frame construction
    bodies have private names; cbind.data.frame selects that private frame
    constructor. Public per-input as.data.frame remains an extension boundary.
    Wrappers preserve eager argument collection, reference snapshots and typed
    result publication. Explicitly selected foreign S3 binding methods retain
    public generic dispatch. No base R tests were copied.
  The first-applicable-method policy in src/main/bind.c was studied for the
    R-level selection helper. That file credits Copyright (C) 1995, 1996
    Robert Gentleman and Ross Ihaka; (C) 1997-2025 The R Core Team; and
    (C) 2002-2020 The R Foundation, under GPL-2-or-later. No C body from that
    file is incorporated; its argument/class dispatch behavior informs the
    public getS3method lookup and selected fallback boundary.

Additional R 4.6.1 source study for Stage 3, with no implementation or tests
copied or adapted from these files:
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/memory.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/attrib.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/coerce.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/summary.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/arithmetic.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/bind.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/altrep.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/errors.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/gnuwin32/system.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/include/R_ext/Itermacros.h
  Resizable-vector, attribute-getter/setter/iterator, protection-stack and
  garbage-collection behavior informed the native append journal and temporary
  names placeholder. The implementation uses the public R 4.6 API. In
  particular, R_mapAttrib is experimental and confined to internal attribute
  inspection and journal roots. It neither publishes names nor changes R
  reference counts. The existing base-row adaptation above is unchanged.
  Read-loop, coercion and concatenation behavior informed owned read pointers,
  the independent ordinary snapshot passed to range, and public integer/logical
  exports through Rf_coerceVector. R's conversion implementation is called
  through its public API, not copied. No owned backing SEXP is passed to an R
  expression or returned as an untracked result.
  Interrupt-handler behavior informed portable native fault injection. The
  tests call the documented Rf_onintr entry after native writes instead of
  relying on platform C signal delivery; no interrupt implementation was copied.

Additional R 4.6.1 source study for Stage 4, SVN revision 90187, with no
implementation or tests copied or adapted:
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/altrep.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/subset.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/coerce.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/memory.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/serialize.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/duplicate.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/attrib.c
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/summary.c
  ALTSTRING element access, writable pointers, subset padding, encoding and
  ordinary serialization informed the extension of package-owned backing to
  characters, logicals and integer/factor columns. The module generalizes the
  package's Stage 3 implementation and uses public R APIs. Native dictionary
  descriptor pins are package-owned Rust code; no upstream implementation was
  incorporated for their lifetime management.
  Attribute-only duplication informed the internal owned-string attribute
  copy boundary, which uses the package's owned fork and Rf_setAttrib. Public
  attribute and names replacement retain R's dispatch and foreign fallbacks.
  Per-element and region read dispatch informed the native gathering and
  writer loops; no R gathering, coercion or aggregate algorithm was copied.
  Repeated subscript validation informed the qualified discrete batch route.
  Factor deep duplication and ordinary logical subset results use the package's
  copy boundary to retain ordinary R read temporaries; public classes and the
  existing fallback dispatch remain unchanged.

Additional R 4.6.1 source study for the scalar bytecode guard:
  https://svn.r-project.org/R/tags/R-4-6-1/src/main/identical.c
  R's bytecode, pairlist and plain-leaf equality semantics informed the
  conservative callback-free comparison in numeric-payload.c. The package
  still calls R_compute_identical for supported leaves after checking for
  nested ALTREP values; no R function body was copied. R's preserved license
  follows below.

Studied as references only, with no dtplyr implementation incorporated:
  dtplyr 1.3.3, revision 2cc627511c34ed461093ae4c5dc94faccffeb93c
  https://github.com/tidyverse/dtplyr/tree/2cc627511c34ed461093ae4c5dc94faccffeb93c
  R/step-subset-select.R, R/step-call.R, R/step-subset.R, and their tests.
  Selection plans and copy flags informed the design review. They do not
  establish the ownership or symmetric isolation required by dibbles. The
  inspected files contain no separate file-level notices. dtplyr's MIT license
  is reproduced for reference; this is not a claim that its code was copied.

data.table source study and .internal.selfref compatibility credit:
  data.table 1.18.6.1 (MPL-2.0). Its DESCRIPTION lists Tyson Barrett,
  Matt Dowle, Arun Srinivasan, Jan Gorecki, Michael Chirico, Toby Hocking,
  Benjamin Schwendinger, and Ivan Krylov as authors, with further contributors.
  https://cran.r-project.org/src/contrib/data.table_1.18.6.1.tar.gz
  Studied archive files: R/data.table.R, src/dogroups.c, src/assign.c,
    src/wrappers.c, src/utils.c, src/reorder.c, NEWS.md, DESCRIPTION,
    and LICENSE.
  Its grouped evaluator, bounded GForce admission, and copy or materialization
  of ALTREP columns at mutation boundaries informed the architecture review
  of dtatools' grouped mutation and owned columns. data.table uses
  by-reference assignment with a different alias contract. The dtatools
  scalar producer and dependency checks are independent code. For data.table
  interoperability, dtatools' data_table_reference_valid() checks the
  .internal.selfref pointer layout defined by data.table's src/assign.c
  setselfref() and _selfrefok() (1.18.6.1, lines 3-84). That compatibility
  check is independently written, but the layout and validity rule come
  from data.table. No data.table grouped evaluator, GForce arithmetic,
  memrecycle assignment loop, or source text was copied into dtatools.

Public tidyselect, rlang, vctrs, tibble and dplyr APIs remain dependencies.
Calling those APIs does not incorporate their implementations. Tibble's index
implementation was inspected to check its public planning API; no tibble
source was copied or adapted. The data.table compatibility rule is credited
above. The bounded vctrs restoration-policy adaptation below is separate
from public API use.

Adapted from vctrs 0.7.3:
  Source archive: https://cran.r-project.org/src/contrib/vctrs_0.7.3.tar.gz
  SHA256: b45078413e06ac624dddb7221a3a43908b405c8abec09822cb86638d30b0435b
  R/type-dplyr.R: vec_restore_grouped_df and vec_restore_rowwise_df policies
  R/zzz.R: conditional grouping-method registration was inspected as reference.
  Destination: vec_restore.dtatools_ref_data in R/mutate-data.R.
  Changes: when grouping methods are absent, restore a plain intermediate,
    apply package typing and owned capture, and rebuild grouping metadata.
    Grouped keys/drop are retained; rowwise restoration removes identifiers.
    Existing visible/registered methods and custom subclasses keep their
    previous dispatch path. No other vctrs implementation is incorporated.

Preserved vctrs license
----------------------

Copyright (c) 2023 vctrs authors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Preserved dplyr license
----------------------

# MIT License

Copyright (c) 2026 dplyr authors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Reference dtplyr license
------------------------

# MIT License

Copyright (c) 2023 dtplyr authors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Preserved R license (R-4-6-1/COPYING)
----------------------------------

		    GNU GENERAL PUBLIC LICENSE
		       Version 2, June 1991

 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
                       51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

			    Preamble

  The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users.  This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it.  (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.)  You can apply it to
your programs, too.

  When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.

  To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.

  For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
rights.

  We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.

  Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software.  If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.

  Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.

  The precise terms and conditions for copying, distribution and
modification follow.

		    GNU GENERAL PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License.  The "Program", below,
refers to any such program or work, and a "work based on the Program"
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language.  (Hereinafter, translation is included without limitation in
the term "modification".)  Each licensee is addressed as "you".

Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope.  The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.

  1. You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.

You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.

  2. You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:

    a) You must cause the modified files to carry prominent notices
    stating that you changed the files and the date of any change.

    b) You must cause any work that you distribute or publish, that in
    whole or in part contains or is derived from the Program or any
    part thereof, to be licensed as a whole at no charge to all third
    parties under the terms of this License.

    c) If the modified program normally reads commands interactively
    when run, you must cause it, when started running for such
    interactive use in the most ordinary way, to print or display an
    announcement including an appropriate copyright notice and a
    notice that there is no warranty (or else, saying that you provide
    a warranty) and that users may redistribute the program under
    these conditions, and telling the user how to view a copy of this
    License.  (Exception: if the Program itself is interactive but
    does not normally print such an announcement, your work based on
    the Program is not required to print an announcement.)

These requirements apply to the modified work as a whole.  If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works.  But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.

Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.

In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.

  3. You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:

    a) Accompany it with the complete corresponding machine-readable
    source code, which must be distributed under the terms of Sections
    1 and 2 above on a medium customarily used for software interchange; or,

    b) Accompany it with a written offer, valid for at least three
    years, to give any third party, for a charge no more than your
    cost of physically performing source distribution, a complete
    machine-readable copy of the corresponding source code, to be
    distributed under the terms of Sections 1 and 2 above on a medium
    customarily used for software interchange; or,

    c) Accompany it with the information you received as to the offer
    to distribute corresponding source code.  (This alternative is
    allowed only for noncommercial distribution and only if you
    received the program in object code or executable form with such
    an offer, in accord with Subsection b above.)

The source code for a work means the preferred form of the work for
making modifications to it.  For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable.  However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.

If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.

  4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.

  5. You are not required to accept this License, since you have not
signed it.  However, nothing else grants you permission to modify or
distribute the Program or its derivative works.  These actions are
prohibited by law if you do not accept this License.  Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.

  6. Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions.  You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.

  7. If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License.  If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all.  For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.

If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.

It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices.  Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.

This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.

  8. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded.  In such case, this License incorporates
the limitation as if written in the body of this License.

  9. The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time.  Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.

Each version is given a distinguishing version number.  If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation.  If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
Foundation.

  10. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission.  For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this.  Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.

			    NO WARRANTY

  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.

  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.

		     END OF TERMS AND CONDITIONS

	    How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA


Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:

    Gnomovision version 69, Copyright (C) year name of author
    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary.  Here is a sample; alter the names:

  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
  `Gnomovision' (which makes passes at compilers) written by James Hacker.

  <signature of Ty Coon>, 1 April 1989
  Ty Coon, President of Vice

This General Public License does not permit incorporating your program into
proprietary programs.  If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library.  If this is what you want to do, use the GNU Library General
Public License instead of this License.

Grouping hash mixer

  src/probe-grouped-bracket-plan.c uses Chris Wellons's lowbias32 mixer from
  hash-prospector (https://github.com/skeeto/hash-prospector), released under
  the Unlicense. The surrounding grouping and publication code is original.
