;;; semantic/analyze.el --- Analyze semantic tags against local context

;; Copyright (C) 2000-2005, 2007-2020 Free Software Foundation, Inc.

;; Author: Eric M. Ludlam <zappo@gnu.org>

;; This file is part of GNU Emacs.

;; GNU Emacs 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 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:
;;
;; Semantic, as a tool, provides a nice list of searchable tags.
;; That information can provide some very accurate answers if the current
;; context of a position is known.
;;
;; Semantic-ctxt provides ways of analyzing, and manipulating the
;; semantic context of a language in code.
;;
;; This library provides routines for finding intelligent answers to
;; tough problems, such as if an argument to a function has the correct
;; return type, or all possible tags that fit in a given local context.
;;

;;; Vocabulary:
;;
;; Here are some words used to describe different things in the analyzer:
;;
;; tag - A single entity
;; prefix - The beginning of a symbol, usually used to look up something
;;       incomplete.
;; type - The name of a datatype in the language.
;; metatype - If a type is named in a declaration like:
;;       struct moose somevariable;
;;       that name "moose" can be turned into a concrete type.
;; tag sequence - In C code, a list of dereferences, such as:
;;       this.that.theother();
;; parent - For a datatype in an OO language, another datatype
;;       inherited from.  This excludes interfaces.
;; scope - A list of tags that can be dereferenced that cannot
;;       be found from the global namespace.
;; scopetypes - A list of tags which are datatype that contain
;;       the scope.  The scopetypes need to have the scope extracted
;;       in a way that honors the type of inheritance.
;; nest/nested - When one tag is contained entirely in another.
;;
;; context - A semantic datatype representing a point in a buffer.
;;
;; constraint - If a context specifies a specific datatype is needed,
;;       that is a constraint.
;; constants - Some datatypes define elements of themselves as a
;;       constant.  These need to be returned as there would be no
;;       other possible completions.

(require 'semantic)
(require 'semantic/format)
(require 'semantic/ctxt)
(require 'semantic/scope)
(require 'semantic/sort)
(require 'semantic/analyze/fcn)

(eval-when-compile (require 'semantic/find))

(declare-function data-debug-new-buffer "data-debug")
(declare-function data-debug-insert-object-slots "eieio-datadebug")

;;; Code:
(defvar semantic-analyze-error-stack nil
  "Collection of any errors thrown during analysis.")

(defun semantic-analyze-push-error (err)
  "Push the error data in ERR onto the error stack."
  (push err semantic-analyze-error-stack))

;;; Analysis Classes
;;
;; These classes represent what a context is.  Different types
;; of contexts provide differing amounts of information to help
;; provide completions.
;;
(defclass semantic-analyze-context ()
  ((bounds :initarg :bounds
	   :type list
	   :documentation "The bounds of this context.
Usually bound to the dimension of a single symbol or command.")
   (prefix :initarg :prefix
	   :type list
	   :documentation "List of tags defining local text.
This can be nil, or a list where the last element can be a string
representing text that may be incomplete.  Preceding elements
must be semantic tags representing variables or functions
called in a dereference sequence.")
   (prefixclass :initarg :prefixclass
		:type list
		:documentation "Tag classes expected at this context.
These are classes for tags, such as 'function, or 'variable.")
   (prefixtypes :initarg :prefixtypes
	   :type list
	   :documentation "List of tags defining types for :prefix.
This list is one shorter than :prefix.  Each element is a semantic
tag representing a type matching the semantic tag in the same
position in PREFIX.")
   (scope :initarg :scope
	  :type (or null semantic-scope-cache)
	  :documentation "List of tags available in scopetype.
See `semantic-analyze-scoped-tags' for details.")
   (buffer :initarg :buffer
	   :type buffer
	   :documentation "The buffer this context is derived from.")
   (errors :initarg :errors
	   :documentation "Any errors thrown and caught during analysis.")
   )
  "Base analysis data for any context.")

(defclass semantic-analyze-context-assignment (semantic-analyze-context)
  ((assignee :initarg :assignee
	     :type list
	     :documentation "A sequence of tags for an assignee.
This is a variable into which some value is being placed.  The last
item in the list is the variable accepting the value.  Earlier
tags represent the variables being dereferenced to get to the
assignee."))
  "Analysis class for a value in an assignment.")

(defclass semantic-analyze-context-functionarg (semantic-analyze-context)
  ((function :initarg :function
	     :type list
	     :documentation "A sequence of tags for a function.
This is a function being called.  The cursor will be in the position
of an argument.
The last tag in :function is the function being called.  Earlier
tags represent the variables being dereferenced to get to the
function.")
   (index :initarg :index
	  :type integer
	  :documentation "The index of the argument for this context.
If a function takes 4 arguments, this value should be bound to
the values 1 through 4.")
   (argument :initarg :argument
	     :type list
	     :documentation "A sequence of tags for the :index argument.
The argument can accept a value of some type, and this contains the
tag for that definition.  It should be a tag, but might
be just a string in some circumstances.")
   )
  "Analysis class for a value as a function argument.")

(defclass semantic-analyze-context-return (semantic-analyze-context)
  () ; No extra data.
  "Analysis class for return data.
Return data methods identify the required type by the return value
of the parent function.")

;;; METHODS
;;
;; Simple methods against the context classes.
;;
(cl-defmethod semantic-analyze-type-constraint
  ((context semantic-analyze-context) &optional desired-type)
  "Return a type constraint for completing :prefix in CONTEXT.
Optional argument DESIRED-TYPE may be a non-type tag to analyze."
  (when (semantic-tag-p desired-type)
    ;; Convert the desired type if needed.
    (if (not (eq (semantic-tag-class desired-type) 'type))
	(setq desired-type (semantic-tag-type desired-type)))
    ;; Protect against plain strings
    (cond ((stringp desired-type)
	   (setq desired-type (list desired-type 'type)))
	  ((and (stringp (car desired-type))
		(not (semantic-tag-p desired-type)))
	   (setq desired-type (list (car desired-type) 'type)))
	  ((semantic-tag-p desired-type)
	   ;; We have a tag of some sort.  Yay!
	   nil)
	  (t (setq desired-type nil))
	  )
    desired-type))

(cl-defmethod semantic-analyze-type-constraint
  ((context semantic-analyze-context-functionarg))
  "Return a type constraint for completing :prefix in CONTEXT."
  (cl-call-next-method context (car (oref context argument))))

(cl-defmethod semantic-analyze-type-constraint
  ((context semantic-analyze-context-assignment))
  "Return a type constraint for completing :prefix in CONTEXT."
  (cl-call-next-method context (car (reverse (oref context assignee)))))

(cl-defmethod semantic-analyze-interesting-tag
  ((context semantic-analyze-context))
  "Return a tag from CONTEXT that would be most interesting to a user."
  (let ((prefix (reverse (oref context prefix))))
    ;; Go back through the prefix until we find a tag we can return.
    (while (and prefix (not (semantic-tag-p (car prefix))))
      (setq prefix (cdr prefix)))
    ;; Return the found tag, or nil.
    (car prefix)))

(cl-defmethod semantic-analyze-interesting-tag
  ((context semantic-analyze-context-functionarg))
  "Try the base, and if that fails, return what we are assigning into."
  (or (cl-call-next-method) (car-safe (oref context function))))

(cl-defmethod semantic-analyze-interesting-tag
  ((context semantic-analyze-context-assignment))
  "Try the base, and if that fails, return what we are assigning into."
  (or (cl-call-next-method) (car-safe (oref context assignee))))

;;; ANALYSIS
;;
;; Start out with routines that will calculate useful parts of
;; the general analyzer function.  These could be used directly
;; by an application that doesn't need to calculate the full
;; context.

(define-overloadable-function semantic-analyze-find-tag-sequence
  (sequence &optional scope typereturn throwsym &rest flags)
  "Attempt to find all tags in SEQUENCE.
Optional argument LOCALVAR is the list of local variables to use when
finding the details on the first element of SEQUENCE in case
it is not found in the global set of tables.
Optional argument SCOPE are additional terminals to search which are currently
scoped.  These are not local variables, but symbols available in a structure
which doesn't need to be dereferenced.
Optional argument TYPERETURN is a symbol in which the types of all found
will be stored.  If nil, that data is thrown away.
Optional argument THROWSYM specifies a symbol the throw on non-recoverable error.
Remaining arguments FLAGS are additional flags to apply when searching.")

(defun semantic-analyze-find-tag-sequence-default
  ;; Note: overloadable fcn uses &rest, but it is a list already, so we don't need
  ;; to do that in the -default.
  (sequence &optional scope typereturn throwsym flags)
  "Attempt to find all tags in SEQUENCE.
SCOPE are extra tags which are in scope.
TYPERETURN is a symbol in which to place a list of tag classes that
are found in SEQUENCE.
Optional argument THROWSYM specifies a symbol the throw on non-recoverable error.
Remaining arguments FLAGS are additional flags to apply when searching.
This function knows of flags:
  `mustbeclassvariable'"
  (let ((s sequence)			; copy of the sequence
	(tmp nil)			; tmp find variable
	(tag nil)			; tag return list
	(tagtype nil)			; tag types return list
	(fname nil)
	(miniscope (when scope (clone scope)))
	(tagclass (if (memq 'mustbeclassvariable flags)
		      'variable nil))
	)
    ;; First order check.  Is this wholly contained in the typecache?
    (setq tmp (semanticdb-typecache-find sequence))

    (when tmp
      (if (or (not tagclass) (semantic-tag-of-class-p tmp tagclass))
	  ;; We are effectively done...
	  (setq s nil
		tag (list tmp))
	;; tagclass doesn't match, so fail this.
	(setq tmp nil)))

    (unless tmp
      ;; For tag class filtering, only apply the filter if the first entry
      ;; is also the only entry.
      (let ((lftagclass (if (= (length s) 1) tagclass)))

	;; For the first entry, it better be a variable, but it might
	;; be in the local context too.
	;; NOTE: Don't forget c++ namespace foo::bar.
	(setq tmp (or
		   ;; Is this tag within our scope.  Scopes can sometimes
		   ;; shadow other things, so it goes first.
		   (and scope (semantic-scope-find (car s) lftagclass scope))
		   ;; Find the tag out there... somewhere, but not in scope
		   (semantic-analyze-find-tag (car s) lftagclass)
		   ))

	(if (and (listp tmp) (semantic-tag-p (car tmp)))
	    (setq tmp (semantic-analyze-select-best-tag tmp lftagclass)))
	(if (not (semantic-tag-p tmp))
	    (if throwsym
		(throw throwsym "Cannot find definition")
	      (error "Cannot find definition for \"%s\"" (car s))))
	(setq s (cdr s))
	(setq tag (cons tmp tag)) ; tag is nil here...
	(setq fname (semantic-tag-file-name tmp))
	))

    ;; For the middle entries
    (while s
      ;; Using the tag found in TMP, let's find the tag
      ;; representing the full typeographic information of its
      ;; type, and use that to determine the search context for
      ;; (car s)
      (let* ((tmptype
	      ;; In some cases the found TMP is a type,
	      ;; and we can use it directly.
	      (cond ((semantic-tag-of-class-p tmp 'type)
		     (or (semantic-analyze-type tmp miniscope)
			 tmp))
		    (t
		     (semantic-analyze-tag-type tmp miniscope))))
	     (typefile
	      (when tmptype
		(semantic-tag-file-name tmptype)))
	     (slots nil))

	;; Get the children
	(setq slots (semantic-analyze-scoped-type-parts tmptype scope))

	;; find (car s) in the list o slots
	(setq tmp (semantic-find-tags-by-name (car s) slots))

	;; If we have lots
	(if (and (listp tmp) (semantic-tag-p (car tmp)))
	    (setq tmp (semantic-analyze-select-best-tag tmp)))

	;; Make sure we have a tag.
	(if (not (semantic-tag-p tmp))
	    (if (cdr s)
		;; In the middle, we need to keep seeking our types out.
		(error "Cannot find definition for \"%s\"" (car s))
	      ;; Else, it's ok to end with a non-tag
	      (setq tmp (car s))))

	(setq fname (or typefile fname))
	(when (and fname (semantic-tag-p tmp)
		   (not (semantic-tag-in-buffer-p tmp)))
	  (semantic--tag-put-property tmp :filename fname))
	(setq tag (cons tmp tag))
	(setq tagtype (cons tmptype tagtype))
	(when miniscope
	  (let ((rawscope
		 (apply 'append
			(mapcar 'semantic-tag-type-members tagtype))))
	    (oset miniscope fullscope rawscope)))
	)
      (setq s (cdr s)))

    (if typereturn (set typereturn (nreverse tagtype)))
    ;; Return the mess
    (nreverse tag)))

(defun semantic-analyze-find-tag (name &optional tagclass scope)
  "Return the first tag found with NAME or nil if not found.
Optional argument TAGCLASS specifies the class of tag to return,
such as `function' or `variable'.
Optional argument SCOPE specifies a scope object which has
additional tags which are in SCOPE and do not need prefixing to
find.

This is a wrapper on top of semanticdb, semanticdb typecache,
semantic-scope, and semantic search functions.  Almost all
searches use the same arguments."
  (let ((namelst (if (consp name) name ;; test if pre-split.
		   (semantic-analyze-split-name name))))
    (cond
     ;; If the splitter gives us a list, use the sequence finder
     ;; to get the list.  Since this routine is expected to return
     ;; only one tag, return the LAST tag found from the sequence
     ;; which is supposedly the nested reference.
     ;;
     ;; Of note, the SEQUENCE function below calls this function
     ;; (recursively now) so the names that we get from the above
     ;; fcn better not, in turn, be splittable.
     ((listp namelst)
      ;; If we had a split, then this is likely a c++ style namespace::name sequence,
      ;; so take a short-cut through the typecache.
      (or (semanticdb-typecache-find namelst)
	  ;; Ok, not there, try the usual...
	  (let ((seq (semantic-analyze-find-tag-sequence
		      namelst scope nil)))
	    (semantic-analyze-select-best-tag seq tagclass)
	    )))
     ;; If NAME is solo, then do our searches for it here.
     ((stringp namelst)
      (let ((retlist (and scope (semantic-scope-find name tagclass scope))))
	(if retlist
	    (semantic-analyze-select-best-tag
	     retlist tagclass)
	  (if (eq tagclass 'type)
	      (semanticdb-typecache-find name)
	    ;; Search in the typecache.  First entries in a sequence are
	    ;; often there.
	    (setq retlist (semanticdb-typecache-find name))
	    (if (and retlist (or (not tagclass)
				 (semantic-tag-of-class-p retlist 'tagclass)))
		retlist
	      (semantic-analyze-select-best-tag
	       (semanticdb-strip-find-results
		(semanticdb-find-tags-by-name name)
		'name)
	       tagclass)
	      )))))
     )))

;;; SHORT ANALYSIS
;;
;; Create a mini-analysis of just the symbol under point.
;;
(define-overloadable-function semantic-analyze-current-symbol
  (analyzehookfcn &optional position)
  "Call ANALYZEHOOKFCN after analyzing the symbol under POSITION.
The ANALYZEHOOKFCN is called with the current symbol bounds, and the
analyzed prefix.  It should take the arguments (START END PREFIX).
The ANALYZEHOOKFCN is only called if some sort of prefix with bounds was
found under POSITION.

The results of ANALYZEHOOKFCN is returned, or nil if there was nothing to
call it with.

For regular analysis, you should call `semantic-analyze-current-context'
to calculate the context information.  The purpose for this function is
to provide a large number of non-cached analysis for filtering symbols."
  ;; Only do this in a Semantic enabled buffer.
  (when (not (semantic-active-p))
    (error "Cannot analyze buffers not supported by Semantic"))
  ;; Always refresh out tags in a safe way before doing the
  ;; context.
  (semantic-refresh-tags-safe)
  ;; Do the rest of the analysis.
  (save-match-data
    (save-excursion
      (:override)))
  )

(defun semantic-analyze-current-symbol-default (analyzehookfcn position)
  "Call ANALYZEHOOKFCN on the analyzed symbol at POSITION."
  (let* ((semantic-analyze-error-stack nil)
	 ;; (LLstart (current-time))
	 (prefixandbounds (semantic-ctxt-current-symbol-and-bounds (or position (point))))
	 (prefix (car prefixandbounds))
	 (bounds (nth 2 prefixandbounds))
	 (scope (semantic-calculate-scope position))
	 )
        ;; Only do work if we have bounds (meaning a prefix to complete)
    (when bounds

      (if debug-on-error
	  (catch 'unfindable
	    ;; If debug on error is on, allow debugging in this fcn.
	    (setq prefix (semantic-analyze-find-tag-sequence
			  prefix scope 'prefixtypes 'unfindable)))
	;; Debug on error is off.  Capture errors and move on
	(condition-case err
	    ;; NOTE: This line is duplicated in
	    ;;       semantic-analyzer-debug-global-symbol
	    ;;       You will need to update both places.
	    (setq prefix (semantic-analyze-find-tag-sequence
			  prefix scope 'prefixtypes))
	  (error (semantic-analyze-push-error err))))

      ;;(message "Analysis took %.2f sec" (semantic-elapsed-time LLstart nil))

      )
    (when prefix
      (prog1
	  (funcall analyzehookfcn (car bounds) (cdr bounds) prefix)
	;;(message "hookfcn took %.5f sec" (semantic-elapsed-time LLstart nil))
	)

	)))

;;; MAIN ANALYSIS
;;
;; Create a full-up context analysis.
;;
;;;###autoload
(define-overloadable-function semantic-analyze-current-context (&optional position)
  "Analyze the current context at optional POSITION.
If called interactively, display interesting information about POSITION
in a separate buffer.
Returns an object based on symbol `semantic-analyze-context'.

This function can be overridden with the symbol `analyze-context'.
When overriding this function, your override will be called while
cursor is at POSITION.  In addition, your function will not be called
if a cached copy of the return object is found."
  (interactive "d")
  ;; Only do this in a Semantic enabled buffer.
  (when (not (semantic-active-p))
    (error "Cannot analyze buffers not supported by Semantic"))
  ;; Always refresh out tags in a safe way before doing the
  ;; context.
  (semantic-refresh-tags-safe)
  ;; Do the rest of the analysis.
  (if (not position) (setq position (point)))
  (save-excursion
    (goto-char position)
    (let* ((answer (semantic-get-cache-data 'current-context)))
      (with-syntax-table semantic-lex-syntax-table
	(when (not answer)
	  (setq answer (:override))
	  (when (and answer (oref answer bounds))
	    (with-slots (bounds) answer
	      (semantic-cache-data-to-buffer (current-buffer)
					     (car bounds)
					     (cdr bounds)
					     answer
					     'current-context
					     'exit-cache-zone)))
	  ;; Check for interactivity
	  (when (called-interactively-p 'any)
	    (if answer
		(semantic-analyze-pop-to-context answer)
	      (message "No Context."))
	    ))

	answer))))

(defun semantic-analyze-current-context-default (position)
  "Analyze the current context at POSITION.
Returns an object based on symbol `semantic-analyze-context'."
  (let* ((semantic-analyze-error-stack nil)
	 (context-return nil)
	 (prefixandbounds (semantic-ctxt-current-symbol-and-bounds (or position (point))))
	 (prefix (car prefixandbounds))
	 (bounds (nth 2 prefixandbounds))
	 ;; @todo - vv too early to really know this answer! vv
	 (prefixclass (semantic-ctxt-current-class-list))
	 (prefixtypes nil)
	 (scope (semantic-calculate-scope position))
	 (function nil)
	 (fntag nil)
	 arg fntagend argtag
	 assign asstag newseq
	 )

    ;; Pattern for Analysis:
    ;;
    ;; Step 1: Calculate DataTypes in Scope:
    ;;
    ;;  a) Calculate the scope (above)
    ;;
    ;; Step 2: Parse context
    ;;
    ;; a) Identify function being called, or variable assignment,
    ;;    and find source tags for those references
    ;; b) Identify the prefix (text cursor is on) and find the source
    ;;    tags for those references.
    ;;
    ;; Step 3: Assemble an object
    ;;

    ;; Step 2 a:

    (setq function (semantic-ctxt-current-function))

    (when function
      ;; Calculate the argument for the function if there is one.
      (setq arg (semantic-ctxt-current-argument))

      ;; Find a tag related to the function name.
      (condition-case err
	  (setq fntag
		(semantic-analyze-find-tag-sequence function scope))
	(error (semantic-analyze-push-error err)))

      ;; fntag can have the last entry as just a string, meaning we
      ;; could not find the core datatype.  In this case, the searches
      ;; below will not work.
      (when (stringp (car (last fntag)))
	;; Take a wild guess!
	(setcar (last fntag) (semantic-tag (car (last fntag)) 'function))
	)

      (when fntag
	(let ((fcn (semantic-find-tags-by-class 'function fntag)))
	  (when (not fcn)
	    (let ((ty (semantic-find-tags-by-class 'type fntag)))
	      (when ty
		;; We might have a constructor with the same name as
		;; the found datatype.
		(setq fcn (semantic-find-tags-by-name
			   (semantic-tag-name (car ty))
			   (semantic-tag-type-members (car ty))))
		(if fcn
		    (let ((lp fcn))
		      (while lp
			(when (semantic-tag-get-attribute (car lp)
							  :constructor)
			  (setq fcn (cons (car lp) fcn)))
			(setq lp (cdr lp))))
		  ;; Give up, go old school
		  (setq fcn fntag))
		)))
	  (setq fntagend (car (reverse fcn))
		argtag
		(when (semantic-tag-p fntagend)
		  (nth (1- arg) (semantic-tag-function-arguments fntagend)))
		fntag fcn))))

    ;; Step 2 b:

    ;; Only do work if we have bounds (meaning a prefix to complete)
    (when bounds

      (if debug-on-error
	  (catch 'unfindable
	    (setq prefix (semantic-analyze-find-tag-sequence
			  prefix scope 'prefixtypes 'unfindable))
	    ;; If there's an alias, dereference it and analyze
	    ;; sequence again.
	    (when (setq newseq
			(semantic-analyze-dereference-alias prefix))
	      (setq prefix (semantic-analyze-find-tag-sequence
			    newseq scope 'prefixtypes 'unfindable))))
	;; Debug on error is off.  Capture errors and move on
	(condition-case err
	    ;; NOTE: This line is duplicated in
	    ;;       semantic-analyzer-debug-global-symbol
	    ;;       You will need to update both places.
	    (progn
	      (setq prefix (semantic-analyze-find-tag-sequence
			    prefix scope 'prefixtypes))
	      (when (setq newseq
			  (semantic-analyze-dereference-alias prefix))
		(setq prefix (semantic-analyze-find-tag-sequence
			      newseq scope 'prefixtypes))))
	  (error (semantic-analyze-push-error err))))
      )

    ;; Step 3:

    (cond
     (fntag
      ;; If we found a tag for our function, we can go into
      ;; functional context analysis mode, meaning we have a type
      ;; for the argument.
      (setq context-return
	    (semantic-analyze-context-functionarg
	     :buffer (current-buffer)
	     :function fntag
	     :index arg
	     :argument (list argtag)
	     :scope scope
	     :prefix prefix
	     :prefixclass prefixclass
	     :bounds bounds
	     :prefixtypes prefixtypes
	     :errors semantic-analyze-error-stack)))

      ;; No function, try assignment
     ((and (setq assign (semantic-ctxt-current-assignment))
	   ;; We have some sort of an assignment
	   (condition-case err
	       (setq asstag (semantic-analyze-find-tag-sequence
			     assign scope nil nil 'mustbeclassvariable))
	     (error (semantic-analyze-push-error err)
		    nil)))

      (setq context-return
	    (semantic-analyze-context-assignment
	     :buffer (current-buffer)
	     :assignee asstag
	     :scope scope
	     :bounds bounds
	     :prefix prefix
	     :prefixclass prefixclass
	     :prefixtypes prefixtypes
	     :errors semantic-analyze-error-stack)))

     ;; TODO: Identify return value condition.
     ;;((setq return .... what to do?)
     ;;  ...)

     (bounds
      ;; Nothing in particular
      (setq context-return
	    (semantic-analyze-context
	     :buffer (current-buffer)
	     :scope scope
	     :bounds bounds
	     :prefix prefix
	     :prefixclass prefixclass
	     :prefixtypes prefixtypes
	     :errors semantic-analyze-error-stack)))

     (t (setq context-return nil))
     )

    ;; Return our context.
    context-return))

(defun semantic-analyze-dereference-alias (taglist)
  "Dereference first tag in TAGLIST if it is an alias.
Returns a sequence of names which can then be fed again into
`semantic-analyze-find-tag-sequence'.
Returns nil if no alias was found."
  (when (eq (semantic-tag-get-attribute (car taglist) :kind) 'alias)
    (let ((tagname
	   (semantic-analyze-split-name
	    (semantic-tag-name
	     (car (semantic-tag-get-attribute (car taglist) :members))))))
      (append (if (listp tagname)
		  tagname
		(list tagname))
	      (cdr taglist)))))
\f
(defun semantic-adebug-analyze (&optional ctxt)
  "Perform `semantic-analyze-current-context'.
Display the results as a debug list.
Optional argument CTXT is the context to show."
  (interactive)
  (require 'data-debug)
  (let ((start (current-time))
	(ctxt (or ctxt (semantic-analyze-current-context))))
    (if (not ctxt)
	(message "No Analyzer Results")
      (message "Analysis  took %.2f seconds."
	       (semantic-elapsed-time start nil))
      (semantic-analyze-pulse ctxt)
      (if ctxt
	  (progn
	    (data-debug-new-buffer "*Analyzer ADEBUG*")
	    (data-debug-insert-object-slots ctxt "]"))
	(message "No Context to analyze here.")))))

\f
;;; DEBUG OUTPUT
;;
;; Friendly output of a context analysis.
;;
(declare-function pulse-momentary-highlight-region "pulse")

(cl-defmethod semantic-analyze-pulse ((context semantic-analyze-context))
  "Pulse the region that CONTEXT affects."
  (require 'pulse)
  (with-current-buffer (oref context buffer)
    (let ((bounds (oref context bounds)))
      (when bounds
	(pulse-momentary-highlight-region (car bounds) (cdr bounds))))))

(defcustom semantic-analyze-summary-function 'semantic-format-tag-prototype
  "Function to use when creating items in Imenu.
Some useful functions are found in `semantic-format-tag-functions'."
  :group 'semantic
  :type semantic-format-tag-custom-list)

(defun semantic-analyze-princ-sequence (sequence &optional prefix buff)
  "Send the tag SEQUENCE to standard out.
Use PREFIX as a label.
Use BUFF as a source of override methods."
  ;; If there is no sequence, at least show the field as being empty.
  (unless sequence (princ prefix) (princ "<none>\n"))

  ;; Display the sequence column aligned.
  (while sequence
    (princ prefix)
    (cond
     ((semantic-tag-p (car sequence))
      (princ (funcall semantic-analyze-summary-function
		      (car sequence))))
     ((stringp (car sequence))
      (princ "\"")
      (princ (semantic--format-colorize-text (car sequence) 'variable))
      (princ "\""))
     (t
      (princ (format "'%S" (car sequence)))))
    (princ "\n")
    (setq sequence (cdr sequence))
    (setq prefix (make-string (length prefix) ? ))
    ))

(cl-defmethod semantic-analyze-show ((context semantic-analyze-context))
  "Insert CONTEXT into the current buffer in a nice way."
  (semantic-analyze-princ-sequence (oref context prefix) "Prefix: " )
  (semantic-analyze-princ-sequence (oref context prefixclass) "Prefix Classes: ")
  (semantic-analyze-princ-sequence (oref context prefixtypes) "Prefix Types: ")
  (semantic-analyze-princ-sequence (oref context errors) "Encountered Errors: ")
  (princ "--------\n")
  ;(semantic-analyze-princ-sequence (oref context scopetypes) "Scope Types: ")
  ;(semantic-analyze-princ-sequence (oref context scope) "Scope: ")
  ;(semantic-analyze-princ-sequence (oref context localvariables) "LocalVars: ")
  (when (oref context scope)
    (semantic-analyze-show (oref context scope)))
  )

(cl-defmethod semantic-analyze-show ((context semantic-analyze-context-assignment))
  "Insert CONTEXT into the current buffer in a nice way."
  (semantic-analyze-princ-sequence (oref context assignee) "Assignee: ")
  (cl-call-next-method))

(cl-defmethod semantic-analyze-show ((context semantic-analyze-context-functionarg))
  "Insert CONTEXT into the current buffer in a nice way."
  (semantic-analyze-princ-sequence (oref context function) "Function: ")
  (princ "Argument Index: ")
  (princ (oref context index))
  (princ "\n")
  (semantic-analyze-princ-sequence (oref context argument) "Argument: ")
  (cl-call-next-method))

(defun semantic-analyze-pop-to-context (context)
  "Display CONTEXT in a temporary buffer.
CONTEXT's content is described in `semantic-analyze-current-context'."
  (semantic-analyze-pulse context)
  (with-output-to-temp-buffer "*Semantic Context Analysis*"
    (princ "Context Type: ")
    (princ (eieio-object-name context))
    (princ "\n")
    (princ "Bounds: ")
    (princ (oref context bounds))
    (princ "\n")
    (semantic-analyze-show context)
    )
  (shrink-window-if-larger-than-buffer
   (get-buffer-window "*Semantic Context Analysis*"))
  )


;;; Completion At Point functions
(defun semantic-analyze-completion-at-point-function ()
  "Return possible analysis completions at point.
The completions provided are via `semantic-analyze-possible-completions'.
This function can be used by `completion-at-point-functions'."
  (when (semantic-active-p)
    (let* ((ctxt (semantic-analyze-current-context))
           (possible (semantic-analyze-possible-completions ctxt)))

      ;; The return from this is either:
      ;; nil - not applicable here.
      ;; A list: (START END COLLECTION . PROPS)
      (when possible
        (list (car (oref ctxt bounds))
              (cdr (oref ctxt bounds))
              possible))
      )))

(defun semantic-analyze-notc-completion-at-point-function ()
  "Return possible analysis completions at point.
The completions provided are via `semantic-analyze-possible-completions',
but with the `no-tc' option passed in, which means constraints based
on what is being assigned to are ignored.
This function can be used by `completion-at-point-functions'."
  (when (semantic-active-p)
    (let* ((ctxt (semantic-analyze-current-context))
           (possible (semantic-analyze-possible-completions ctxt 'no-tc)))

      (when possible
        (list (car (oref ctxt bounds))
              (cdr (oref ctxt bounds))
              possible))
      )))

(defun semantic-analyze-nolongprefix-completion-at-point-function ()
  "Return possible analysis completions at point.
The completions provided are via `semantic-analyze-possible-completions',
but with the `no-tc' and `no-longprefix' option passed in, which means
constraints resulting in a long multi-symbol dereference are ignored.
This function can be used by `completion-at-point-functions'."
  (when (semantic-active-p)
    (let* ((ctxt (semantic-analyze-current-context))
           (possible (semantic-analyze-possible-completions
                      ctxt 'no-tc 'no-longprefix)))

      (when possible
        (list (car (oref ctxt bounds))
              (cdr (oref ctxt bounds))
              possible))
      )))

(provide 'semantic/analyze)

;; Local variables:
;; generated-autoload-file: "loaddefs.el"
;; generated-autoload-load-name: "semantic/analyze"
;; End:

;;; semantic/analyze.el ends here