0185c4e05a
Implement the P0 View grammar, expr bridge, stateless view Components, and Ebox mount path in a new independent package. Include bilingual architecture and implementation documents plus contract tests.
131 lines
4.8 KiB
EmacsLisp
131 lines
4.8 KiB
EmacsLisp
;;; etaf-component.el --- Stateless ETAF Component definitions -*- lexical-binding: t; -*-
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;; SPDX-License-Identifier: GPL-3.0-or-later
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;;; Commentary:
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;; This first implementation slice owns only the beginner `:view' Component
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;; form. Stateful `:setup', Context, Behaviors, and lifecycle will be added
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;; behind the same Component boundary in later milestones; they are rejected
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;; here instead of silently receiving different semantics.
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;;; Code:
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(require 'cl-lib)
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(require 'etaf-view)
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(define-error 'etaf-component-definition-error
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"Invalid ETAF Component definition"
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'etaf-view-error)
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(defun etaf--component-definition-error (format-string &rest arguments)
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"Signal a Component definition error formatted from FORMAT-STRING."
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(signal 'etaf-component-definition-error
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(list (apply #'format format-string arguments))))
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(defun etaf--parse-component-props (arguments)
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"Return prop names from Component argument declaration ARGUMENTS."
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(unless (proper-list-p arguments)
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(etaf--component-definition-error
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"Component prop declaration must be a proper list: %S" arguments))
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(let ((tail arguments)
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prop-names)
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(when tail
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(unless (eq (pop tail) '&key)
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(etaf--component-definition-error
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"Component props must use (&key NAME ...), got %S" arguments)))
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(dolist (entry tail)
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(unless (symbolp entry)
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(etaf--component-definition-error
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"Component props must be symbols without defaults: %S" entry))
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(when (keywordp entry)
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(etaf--component-definition-error
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"Component prop names must not be keywords: %S" entry))
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(when (memq entry '(nil t))
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(etaf--component-definition-error
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"Component prop name cannot be a constant: %S" entry))
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(when (memq entry prop-names)
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(etaf--component-definition-error
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"Duplicate Component prop: %S" entry))
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(push entry prop-names))
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(nreverse prop-names)))
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(defun etaf--component-view-variable-bindings (props)
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"Return lexical bindings for Component PROP names."
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(mapcar (lambda (prop)
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`(,prop
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(plist-get etaf--component-props
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,(etaf--component-prop-key prop))))
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props))
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;;;###autoload
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(defmacro etaf-define-component (name arguments &rest clauses)
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"Define stateless Component NAME with ARGUMENTS and CLAUSES.
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The implemented P0 form is:
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(etaf-define-component NAME (&key PROPS)
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:view VIEW)
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VIEW is already structural View syntax and does not need quote. Attribute
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values inside VIEW are ordinary Elisp expressions. `:setup', `:styles',
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slots, and lifecycle are intentionally rejected until their owning runtime
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contracts are implemented."
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(declare (indent 2) (debug defun))
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(unless (symbolp name)
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(etaf--component-definition-error
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"Component name must be a symbol: %S" name))
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(let ((docstring (when (stringp (car clauses)) (pop clauses)))
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view-form
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saw-view)
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(while clauses
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(let ((keyword (pop clauses)))
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(unless (keywordp keyword)
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(etaf--component-definition-error
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"Expected a Component definition keyword, got %S" keyword))
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(pcase keyword
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(:view
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(when saw-view
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(etaf--component-definition-error
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"Component %S has duplicate :view" name))
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(unless clauses
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(etaf--component-definition-error
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"Component %S :view has no View" name))
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(setq view-form (pop clauses)
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saw-view t))
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(:setup
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(etaf--component-definition-error
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"Component %S :setup is reserved for the stateful milestone"
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name))
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(:styles
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(etaf--component-definition-error
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"Component %S :styles is reserved for the style milestone"
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name))
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(_
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(etaf--component-definition-error
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"Unknown Component definition keyword %S" keyword)))))
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(unless saw-view
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(etaf--component-definition-error
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"Component %S requires exactly one :view clause" name))
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(let* ((props (etaf--parse-component-props arguments))
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(definition-symbol
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(intern (format "%s--etaf-component-definition" name)))
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(render-lambda
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`(lambda (etaf--component-props _etaf--children)
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(let ,(etaf--component-view-variable-bindings props)
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,(etaf--compile-view-form view-form)))))
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`(progn
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(defconst ,definition-symbol
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(etaf--component-spec-create
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:name ',name
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:props ',props
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:render ,render-lambda)
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,(or docstring
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(format "Definition of ETAF Component `%s'." name)))
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(etaf--register-component ',name ,definition-symbol)
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',name))))
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(provide 'etaf-component)
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;;; etaf-component.el ends here
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