Add/Change: (heading-regexp), (heading) predicates

Closes #64.  Closes #68.

Thanks to Feng Shu (@tumashu) for suggestions.

README.org

@@ -207,8 +207,10 @@ Arguments are listed next to predicate names, where applicable.
 +  =category (&optional categories)= :: Return non-nil if current heading is in one or more of ~CATEGORIES~ (a list of strings).
 +  =done= :: Return non-nil if entry's ~TODO~ keyword is in ~org-done-keywords~.
 +  =habit= :: Return non-nil if entry is a habit.
-+  =heading (&rest regexps)= :: Return non-nil if current entry's heading matches all ~REGEXPS~ (regexp strings).
++  =heading (&rest strings)= :: Return non-nil if current entry's heading matches all ~STRINGS~.  Matching is done case-insensitively.
      -  Aliases: =h=.
++  ~heading-regexp (&rest regexps)~ :: Return non-nil if current entry's heading matches all ~REGEXPS~ (regexp strings).  Matching is done case-insensitively.
+     -  Aliases: ~h*~.
 +  =level (level-or-comparator &optional level)= :: Return non-nil if current heading's outline level matches arguments.  The following forms are accepted: ~(level NUMBER)~: Matches if heading level is ~NUMBER~.  ~(level NUMBER NUMBER)~: Matches if heading level is equal to or between NUMBERs.  ~(level COMPARATOR NUMBER)~: Matches if heading level compares to ~NUMBER~ with ~COMPARATOR~.  ~COMPARATOR~ may be ~<~, ~<=~, ~>~, or ~>=~.
 +  =link (&optional description-or-target &key description target regexp-p)= :: Return non-nil if current heading contains a link matching arguments. ~DESCRIPTION-OR-TARGET~ is matched against the link's description and target.  Alternatively, one or both of ~DESCRIPTION~ and ~TARGET~ may be matched separately.  Without arguments, return non-nil if any link is found.
 +  =outline-path (&rest strings)= :: Return non-nil if current node's outline path matches all of ~STRINGS~.  Each string may appear as a substring in any part of the node's outline path.  For example, the path =Food/Fruits/Grapes= would match ~(olp "Fruit" "Grape")~.
@@ -518,9 +520,11 @@ Simple links may also be written manually in either sexp or non-sexp form, like:
 
 *Added*
 +  Macro =org-ql-defpred=, used to define search predicates.  (See [[file:examples/defpred.org][tutorial]].)
++  Predicate ~heading-regexp~, which matches regular expressions against heading text (alias: ~h*~).
 
 *Changed*
 +  Helm support (including the command =helm-org-ql=) has been moved to a separate package, =helm-org-ql=.
++  Predicate ~heading~ now matches plain strings instead of regular expressions.
 
 *Internal*
 +  Predicates are now defined more cleanly with a macro (=org-ql-defpred=) that consolidates functionality related to each predicate.  This will also allow users to more easily define custom predicates.

org-ql.el

@@ -1027,28 +1027,56 @@ predicates."
                (list :regexp (rx bol (0+ space) ":STYLE:" (1+ space) "habit" (0+ space) eol))))
   :body (org-is-habit-p))
 
-(org-ql-defpred (heading h) (&rest regexps)
-  "Return non-nil if current entry's heading matches all REGEXPS (regexp strings)."
+(org-ql-defpred (heading h) (&rest strings)
+  "Return non-nil if current entry's heading matches all STRINGS.
+Matching is done case-insensitively."
   :normalizers ((`(,predicate-names . ,args)
                  ;; "h" alias.
                  `(heading ,@args)))
+  ;; TODO: Adjust regexp to avoid matching in tag list.
+  :preambles ((`(,predicate-names ,string)
+               ;; Only one string: match with preamble, then let predicate confirm (because
+               ;; the match could be in e.g. the tags rather than the heading text).
+               (list :regexp (rx-to-string `(seq bol (1+ "*") (1+ blank) (0+ nonl)
+                                                 ,string)
+                                           'no-group)
+                     :case-fold t :query query))
+              (`(,predicate-names . ,strings)
+               ;; Multiple strings: use preamble to match against first
+               ;; string, then let the predicate match the rest.
+               (list :regexp (rx-to-string `(seq bol (1+ "*") (1+ blank) (0+ nonl)
+                                                 ,(car strings))
+                                           'no-group)
+                     :case-fold t :query query)))
+  ;; TODO: In Org 9.2+, `org-get-heading' takes 2 more arguments.
+  :body (let ((heading (org-get-heading 'no-tags 'no-todo))
+              (case-fold-search t))
+          (--all? (string-match it heading) strings)))
+
+(org-ql-defpred (heading-regexp h*) (&rest regexps)
+  "Return non-nil if current entry's heading matches all REGEXPS (regexp strings).
+Matching is done case-insensitively."
+  :normalizers ((`(,predicate-names . ,args)
+                 ;; "h" alias.
+                 `(heading-regexp ,@args)))
   ;; MAYBE: Adjust regexp to avoid matching in tag list.
   :preambles ((`(,predicate-names ,regexp)
                ;; Only one regexp: match with preamble, then let predicate confirm (because
                ;; the match could be in e.g. the tags rather than the heading text).
                (list :regexp (rx-to-string `(seq bol (1+ "*") (1+ blank) (0+ nonl)
-                                                 ,regexp)
+                                                 (regexp ,regexp))
                                            'no-group)
-                     :query query))
+                     :case-fold t :query query))
               (`(,predicate-names . ,regexps)
                ;; Multiple regexps: use preamble to match against first
                ;; regexp, then let the predicate match the rest.
                (list :regexp (rx-to-string `(seq bol (1+ "*") (1+ blank) (0+ nonl)
-                                                 ,(car regexps))
+                                                 (regexp ,(car regexps)))
                                            'no-group)
-                     :query query)))
+                     :case-fold t :query query)))
   ;; TODO: In Org 9.2+, `org-get-heading' takes 2 more arguments.
-  :body (let ((heading (org-get-heading 'no-tags 'no-todo)))
+  :body (let ((heading (org-get-heading 'no-tags 'no-todo))
+              (case-fold-search t))
           (--all? (string-match it heading) regexps)))
 
 (org-ql-defpred level (level-or-comparator &optional level)

org-ql.info

@@ -401,10 +401,14 @@ Arguments are listed next to predicate names, where applicable.
      Return non-nil if entry’s ‘TODO’ keyword is in ‘org-done-keywords’.
 ‘habit’
      Return non-nil if entry is a habit.
-‘heading (&rest regexps)’
-     Return non-nil if current entry’s heading matches all ‘REGEXPS’
-     (regexp strings).
+‘heading (&rest strings)’
+     Return non-nil if current entry’s heading matches all ‘STRINGS’.
+     Matching is done case-insensitively.
         • Aliases: h.
+‘‘heading-regexp (&rest regexps)’’
+     Return non-nil if current entry’s heading matches all ‘REGEXPS’
+     (regexp strings).  Matching is done case-insensitively.
+        • Aliases: ‘h*’.
 ‘level (level-or-comparator &optional level)’
      Return non-nil if current heading’s outline level matches
      arguments.  The following forms are accepted: ‘(level NUMBER)’:
@@ -962,10 +966,14 @@ File: README.info,  Node: 06-pre,  Next: 05,  Up: Changelog
 *Added*
    • Macro org-ql-defpred, used to define search predicates.  (See
      tutorial (examples/defpred.org).)
+   • Predicate ‘heading-regexp’, which matches regular expressions
+     against heading text (alias: ‘h*’).
 
    *Changed*
    • Helm support (including the command helm-org-ql) has been moved to
      a separate package, helm-org-ql.
+   • Predicate ‘heading’ now matches plain strings instead of regular
+     expressions.
 
    *Internal*
    • Predicates are now defined more cleanly with a macro
@@ -1477,40 +1485,40 @@ Node: org-ql-sparse-tree7544
 Node: Queries8344
 Node: Non-sexp query syntax9455
 Node: General predicates11162
-Node: Ancestor/descendant predicates16575
-Node: Date/time predicates17703
-Node: Functions / Macros20358
-Node: Agenda-like views20656
-Node: Listing / acting-on results22061
-Node: Custom predicates27683
-Node: Dynamic block31174
-Node: Links33872
-Node: Tips34559
-Node: Changelog34877
-Node: 06-pre35573
-Node: 0536196
-Node: 04937673
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-Node: 04738294
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-Node: 02248114
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-Node: 0248581
-Node: 0152616
-Node: Notes52717
-Node: Comparison with Org Agenda searches52879
-Node: org-sidebar53751
-Node: License54030
+Node: Ancestor/descendant predicates16805
+Node: Date/time predicates17933
+Node: Functions / Macros20588
+Node: Agenda-like views20886
+Node: Listing / acting-on results22291
+Node: Custom predicates27913
+Node: Dynamic block31404
+Node: Links34102
+Node: Tips34789
+Node: Changelog35107
+Node: 06-pre35803
+Node: 0536638
+Node: 04938115
+Node: 04838389
+Node: 04738736
+Node: 04639131
+Node: 04539531
+Node: 04439890
+Node: 04340247
+Node: 04240442
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+Node: 0249023
+Node: 0153058
+Node: Notes53159
+Node: Comparison with Org Agenda searches53321
+Node: org-sidebar54193
+Node: License54472
 
 End Tag Table
 

tests/test-org-ql.el

@@ -656,6 +656,16 @@ RESULTS should be a list of strings as returned by
         (org-ql-expect ('(heading "Take over" "world"))
           '("Take over the world"))))
 
+    (describe "(heading-regexp)"
+      (org-ql-it "with one argument"
+        (org-ql-expect ('(heading-regexp "w.rld"))
+          ;; NOTE: This--correctly--does not match the "Skype with president of
+          ;; Antarctica" heading, which has the tag ":world:" in its heading line.
+          '("Take over the world")))
+      (org-ql-it "with two arguments"
+        (org-ql-expect ('(h* "T.ke over" "wor.*"))
+          '("Take over the world"))))
+
     (describe "(link)"
       (org-ql-it "without arguments"
         (org-ql-expect ('(link))