Recognize and highlight XPCE string comments as docstrings

* sweeprolog.el (sweeprolog-analyze-fragment-to-faces): recognize
string comments.

Recognize and highlight built-in predicate definitions

* sweeprolog.el (sweeprolog-analyze-fragment-to-faces): recognize
"def_swi" and "def_iso" predicate head kinds .

Do not highlight other occurrences of anonymous variables

* sweeprolog.el (sweeprolog-analyze-fragment-variable): check for
anonymous variables ("_").

Fix typos in README.org

Announce recent changes in NEWS.org and bump version to 0.9.0

ADDED: PlUnit tests block skeleton and command for inserting it

* sweeprolog.el (sweeprolog-format-string-as-atom): new function.
(sweeprolog-module-header-skeleton): use define-skeleton, making it a
command instead of a defconst.
(sweeprolog-plunit-testset-skeleton): new skeleton and command.
* sweeprolog-tests: test it.
* README.org ("Writing Tests"): new section.
("Using templates for creating new modules"): rename to "Creating New
Modules".

* (sweeprolog-beginning-of-next-top-term): revise and add tests

Bump version to 0.8.13 (bug fix release)

FIXED: instantiation error in color term normalization

Announce recent changes in NEWS.org and bump version to 0.8.12

New user-option to controlling highlighting of holes

* sweeprolog.el (sweeprolog-highlight-holes): new user-option.
(sweeprolog-analyze-fragment-to-faces): respect it.

Handle module-qualification in next-clause insertion

* sweeprolog.el (sweeprolog-definition-at-point): also return module
name when the head term is qualified.
(sweeprolog-maybe-insert-next-clause): pass module name to...
(sweeprolog-insert-clause): new argument module.
* sweeprolog-tests.el: add a couple of relevant test cases.

* (sweeprolog-hole-face): new face for highlighting holes

FIXED: sweeprolog-beginning-of-next-top-term: other possible loop

* sweeprolog.el (sweeprolog-beginning-of-next-top-term): don't loop
when called in the last term of the buffer
* sweeprolog-tests.el (beginning-of-next-top-term-at-last-clause): new
test case

* (sweeprolog-top-level-mode-map): bind sweeprolog-forward-hole

FIXED: possible infinite loop looking for next term

* sweeprolog.el (sweeprolog-beginning-of-next-top-term): handle
comments more reliably

Use new prolog_interrupt/0 to interrupt top-level threads

* sweeprolog.el (sweeprolog-top-level-signal-default-goal): change
default value to...
* sweep.pl (sweep_interrupt/0): new predicate, backwards compatibility
wrapper for prolog_interrupt/0.

Bump to version 0.8.11

Support defining DCG non-terminals in sweeprolog-insert-term-dwim

* sweep.pl (sweep_color_normalized_/4): expose DCG term "kind" to
Elisp.
* sweeprolog.el (sweeprolog-new-predicate-location-function): change
expected function signature.
(sweeprolog-default-new-predicate-location)
(sweeprolog-new-predicate-location-above-current): update arguments.
(sweeprolog-maybe-define-predicate): support defining DCGs.

Announce recent changes in NEWS.org and bump version to 0.8.10

Have sweeprolog-top-level-signal-current call trace/0 by default

* sweeprolog.el (sweeprolog-top-level-signal-default-goal): new user
option, set to "trace" by default.
(sweeprolog-top-level-signal-current): use it.

Support DCG and SSU rules in sweeprolog-insert-next-clause

* sweeprolog.el (sweeprolog-definition-at-point): also return kind of
neck.
(sweeprolog-maybe-insert-next-clause): pass it to...
(sweeprolog-insert-next-clause): new argument NECK used instead of
hardcoded ":-", use "Body" for clause body instead of "_".
(sweeprolog-identifier-at-point): handle raw meta goals.
* sweeprolog-tests.el: add tests for sweeprolog-insert-term-dwim
inserting clauses with different neck kinds.

Announce recent changes in NEWS.org and bump version to 0.8.9

* (sweeprolog-analyze-fragment-flymake): restrict syntax errors

* (sweeprolog-predicate-completion-at-point): fix pcase match

* (sweeprolog-analyze-fragment-to-faces) fix comment highlighting

Don't error in sweeprolog-analyze-term-at-point

* (sweeprolog-predicate-completion-at-point): use holes for args

* (sweeprolog-identifier-at-point): fix module qualification

* (sweeprolog-maybe-syntax-error-face): don't error in top-level

FIXED: exporting predicates in presence of exported operators

* sweep.pl (sweep_exportable_predicates/2): new predicate.
* sweeprolog.el (sweeprolog--module-term)
(sweeprolog--exportable-predicates)
(sweeprolog-analyze-start-exportable)
(sweeprolog-analyze-fragment-exportable): no longer used, deleted.
(sweeprolog-exportable-predicates): new function.
(sweeprolog-read-exportable-predicate): use it.
(sweeprolog-export-predicate): handle exported operators.

* (sweeprolog-at-beginning-of-top-term-p): handle comments

* sweeprolog.el (sweeprolog-identifier-at-point): check major-mode

Remove imported duplicates in sweep_predicates_collection/2

Use define-auto-insert instead of manual add-to-list

ENHANCED: allow sweeprolog-forward-hole to wrap around

* sweeprolog.el (sweeprolog--next-hole, sweeprolog--previous-hole):
new functions.
(sweeprolog--forward-hole, sweeprolog--backward-hole): add WRAP arg.

Add test and update manual following change in auto-insert

* sweeprolog.el (auto-insert): leave point at module summary

ENHANCED: conditional syntax error highlighting

Update NEWS.org and bump version to 0.8.8

Don't highlight syntax error at the end of the buffer

* sweeprolog.el (sweeprolog--analyze-point): new buffer local
variable.
(sweeprolog-analyze-buffer, sweeprolog-analyze-some-terms): let-bind
it.
(sweeprolog-analyze-fragment-to-faces): check it before applying
sweeprolog-syntax-error-face.

DOC: mention sweeprolog-swipl-path in the manual

Start the top-level TCP server just-in-time

* sweeprolog.el (sweeprolog-init): do not start TCP server
unconditionally
(sweeprolog-top-level): start it here instead, on demand.
* sweep.pl (sweep_top_level_server/2): wait for TCP server thread to
start before returning control to Emacs.
* README.org (The Prolog Top-Level): add implementation note.

Add sweeprolog-analyze-some-terms to after-change-functions

Document and test sweeprolog-electric-layout-mode

*
sweeprolog.el (sweeprolog-electric-layout-post-self-insert-function):
add docstring.
(sweeprolog-electric-layout-mode): expand docstring, indent after
closing brackets.
* sweeprolog-tests.el: add tests.
* README.org (Aligning with multiple spaces): rename to...
(Maintaining Code Layout): new section, including...
(Inserting the Right Number of Spaces)
(Electric Layout mode): new sections.

ADDED: minor mode for automatic whitespace insertion

* sweep.pl (sweep_context_callable/2): only consider the context to be
callable if a neck is present up the tree, i.e. not in the head.
* sweeprolog.el (sweeprolog-context-callable-p): new function,
extracted from (sweeprolog-predicate-completion-at-point)
(sweeprolog-electric-layout-post-self-insert-function): new function.
(sweeprolog-electric-layout-mode): new minor mode.

Simplify completion at point, bump patch version

ENHANCED: revise predicate completion at point

Completion at point now detects whether predicate completion is
appropriate, by parsing Prolog code back from point to determine the
context of point.  If predicate completion is not appropriate,
fallback to atom completion.

ADDED: user option specifying where to define new predicates

* sweeprolog.el (sweeprolog-default-new-predicate-location)
(sweeprolog-new-predicate-location-above-current): new functions.
(sweeprolog-new-predicate-location-function): new user option.
(sweeprolog-maybe-define-predicate): use it.

FIXED: possible error in sweeprolog-describe-predicate

Highlight test case head terms in a dedicated face

DOC: document sweeprolog-xref-project-source-files in the manual

ADDED: new command sweeprolog-xref-project-source-files

FIXED: find user predicate definitions more reliably

Catch error in kill-buffer-hook when top-level thread is dead

Bump version to 0.8.4

TEST: add test for updating syntax error faces

Recognize backslash as part of an operator in tokenization

FIXED: clear syntax error face after fix more aggressively

FIXED: properly update query highlighting in the toplevel

FIXED: simplify & make variable highlighting more reliable

FIXED: only consider backslash as an escape inside strings

FIXED: restrict variable underlining to current clause

FIXED: variable name completion on Emacs 27

* sweeprolog.el (sweeprolog-variable-completion-at-point): don't rely
on char-uppercase-p
* sweeprolog-tests.el (complete-variable): new test.

ADDED: sweeprolog-forward/backward/mark-predicate

REFACTOR: Simplify and deduplicate code all around

* sweeprolog.el (sweeprolog-colourise-*): rename to sweeprolog-analyze-*

FIXED: correctly recognize "public" head terms

TEST: add two test cases

FIXED: sweeprolog-identifier-at-point could return unbound module

Fixed defcustom type for sweeprolog-top-level-display-action

FIXED: write_sweep_module_location/0 for Windows.

Use term_string/2 to parse M:F/N terms encoded in strings

Organize and split sweeprolog.el into sections

Adhere to the convention of using "Emacs's" instead of "Emacs'"

DOC: added section "Code Completion" to the manual

ADDED: completion-at-point for variable names

* sweeprolog.el (sweeprolog-local-variables-collection,
sweeprolog-variable-completion-at-point): new
functions. (sweeprolog-mode): add to
completion-at-point-functions. (sweeprolog-mode-syntax-table): update
according to char_type(Char, prolog_symbol).

Update NEWS.org and bump package version

ADDED: context-based command for inserting new clauses or terms

* sweeprolog.el (sweeprolog--forward-hole, sweeprolog--backward-hole):
new functions.
(sweeprolog-forward-hole): new command.
(sweeprolog-end-of-predicate-definition,sweeprolog-insert-clause,
sweeprolog-maybe-insert-next-clause,
sweeprolog-maybe-define-predicate): new functions.
(sweeprolog-insert-term-functions): new hook.
(sweeprolog-insert-term-dwim): new command.
(sweeprolog-mode-map): bind new commands.
* sweeprolog-tests.el (dwim-define-predicate): new test case.
* README.org (Context-Based Term Insertion): new section.

ENHANCED: render refs to Prolog library in help buffers

* sweeprolog.el (sweeprolog-render-html-a): recognize and render
references to Prolog library files.

Handle operators that contain '.' more reliably

FIXED: handling of operators as predicate completion candidates

FIXED: don't include irrelevant candidates in apropos results

* sweep.pl (sweep_predicate_apropos/2): filter candidates by minimum
match quality.

ENHANCED: add predicate properties list in help buffers

* sweep.pl (sweep_predicate_properties/2): new predicate.
* sweeprolog.el (sweeprolog--render-predicate-properties): new
function.
(sweeprolog--describe-predicate): use it.

ENHANCED: load and initialize sweep-module just-in-time

Instead of loading sweep-module and initializing Prolog as part of
loading sweeprolog.el (subject to the user option
sweeprolog-init-on-load), this commit introduces just-in-time loading
and initialization of Prolog.  Suggested by Stefan Monnier.

* sweeprolog.el: (sweeprolog--open-query): new function, wraps
sweeprolog-open-query and initializes Prolog on the first call. Used
in place of sweeprolog-open-query throughout.
(sweeprolog-init-on-load): make variable obsolete.

ENHANCED: teach sweep to jump to C code for built-in predicates

* sweeprolog.el:
- sweeprolog-swipl-sources: new user option.
- sweeprolog-native-predicate-location: new function.
- sweeprolog-predicate-location: use it.
- README.org: Built-in Native Predicates: new section.

sweeprolog-describe-predicate compatibility with Emacs 27

ENHANCED: prompt for sweeprolog-describe-predicate

Following feedback from Jan Wielemaker

FIXED: additional compatibility issue with buttons

FIXED: sweeprolog-describe-predicate compatibility with Emacs 28

ADDED: new command for showing help for Prolog predicates

* sweep.pl: sweep_predicate_html_documentation/2: new predicate
* sweeprolog.el:
- sweeprolog-read-predicate-history: new variable.
- sweeprolog-read-predicate: use it, and default to the predicate at
point.
- sweeprolog--colour-term-to-faces: quote symbol
- sweeprolog-describe-predicate: new command.
- sweeprolog-help-prefix-map: bind it.
* README.org: Prolog Help: mention it.

Use list notation for format/2

Extracted locating libswipl and sweep-module to sweep_link.pl

ADDED: new command for showing help for Prolog modules

* sweep.pl: sweep_module_html_documentation/2: new predicate.
* sweeprolog.el:
- sweeprolog-read-module-history: new variable.
- sweeprolog-read-module-name: use it.
- sweeprolog--describe-module: new function.
- sweeprolog-describe-module: new command.
- sweeprolog-help-prefix-map: new keymap.
- sweeprolog-prefix-map: bind it keymap to `h'.
* README.org: Prolog Help: new section.

ENHANCED: update xref data for buffer after exporting predicate

FIXED: possible loop finding start of clause at start of buffer

ADDED: new command for exporting Prolog predicates

* sweep.pl: sweep_local_predicate_export_comment/2: new predicate.
* sweeprolog.el:
- sweeprolog-read-exportable-predicate-prompt: new user option.
- sweeprolog--exportable-predicates: new buffer local variable.
- sweeprolog--colour-term-to-faces: accumulate exportable predicates.
- sweeprolog-colourise-buffer: reset sweeprolog--exportable-predicates.
- sweeprolog-export-predicate: new command.
- sweeprolog-mode-map: bind it.
- sweeprolog-menu: bind it.
- README.org: document it.

DOC: mention new sweep Prolog flag in README.org and NEWS.org

FIXED: sweep_identifier_at_point/2: possible infinite failure loop

FIXED: disregard stderr when invoking write_sweep_module_location

ENHANCED: create Prolog flag sweep=true when running under sweep