/usr/share/ada/adainclude/opentoken/html_lexer.ads is in libopentoken5-dev 6.0b-4.
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--
-- Copyright (C) 2009, 2010, 2013, 2014 Stephen Leake
-- Copyright (C) 1999, 2000 Christoph Karl Walter Grein
--
-- This file is part of the OpenToken package.
--
-- The OpenToken package 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, or (at your option)
-- any later version. The OpenToken package 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 distributed with the OpenToken
-- package; see file GPL.txt. If not, write to the Free Software Foundation,
-- 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
--
-- As a special exception, if other files instantiate generics from
-- this unit, or you link this unit with other files to produce an
-- executable, this unit does not by itself cause the resulting
-- executable to be covered by the GNU General Public License. This
-- exception does not however invalidate any other reasons why the
-- executable file might be covered by the GNU Public License.
-------------------------------------------------------------------------------
with Ada.Strings.Unbounded;
with OpenToken.Token.Enumerated.Analyzer;
package HTML_Lexer is
----------------------------------------------------------------------
-- Utilities for a lexical analyser for the HTML language.
--
-- See the child packages HTML_Lexer.Task_Safe, .Task_Unsafe for
-- the actual lexers.
--
----------------------------------------------------------------------
type Token_Name is
(
-- Syntax error
Bad_Token,
-- Comments <!-- anything -->
Comment,
Whitespace,
-- Document Type Declaration <!DOCTYPE attributes>
Document_Type, -- treated as a comment
-- Tag delimiters
Start_Tag_Opener, -- <
End_Tag_Opener, -- </
Tag_Closer, -- >
-- Tags (without delimiters), not all tags may have attributes
Anchor, -- <A attributes>
HTML, -- <HTML attributes>
HTML_Body, -- <BODY attributes>
Head, -- <HEAD attributes>
Heading_1, -- <H1 attributes>
Image, -- <IMG attributes>
Meta, -- <META attributes>
Pre, -- <pre> ... </pre>, treated as a comment
Title, -- <TITLE attributes>
-- Attributes (Attribute=value)
Content, -- CONTENT
Hyper_Reference, -- HREF
Name, -- NAME
Link_Type, -- TYPE
Source, -- SRC
-- The assignment character in attributes
Assignment, -- =
-- Values (the right side of assignments)
Value, -- unquoted
String, -- "quoted"
-- Running text and entities like &
Text,
Entity,
End_Of_File);
type HTML_Token is private;
function Name (Token : in HTML_Token) return Token_Name;
function Lexeme (Token : in HTML_Token) return Standard.String;
function Line (Token : in HTML_Token) return Natural;
function Column (Token : in HTML_Token) return Natural;
private
type HTML_Token is record
Name : Token_Name;
Lexeme : Ada.Strings.Unbounded.Unbounded_String;
Line : Natural;
Column : Natural;
end record;
-- Visible for children
package Master_Token is new OpenToken.Token.Enumerated
(Token_Name, Token_Name'First, Token_Name'Last, Token_Name'Image);
package Tokenizer is new Master_Token.Analyzer;
-----------------------------------------------------------------------
-- HTML syntax is very different from Ada or Java syntax. This is an
-- abbreviated excerpt of the HTML 4.0 Reference.
--
-- Elements are the structures that describe parts of an HTML
-- document ... An element has three parts: a start tag, content,
-- and an end tag. A tag is special text--"markup"--that is
-- delimited by "<" and ">". An end tag includes a "/" after the
-- "<" ... The start and end tags surround the content of the
--- element:
-- <EM>This is emphasized text</EM>
-- ... An element's attributes define various properties for the
-- element ...
--
-- <IMG SRC="wdglogo.gif" ALT="Web Design Group">
--
-- An attribute is included in the start tag only--never the end
-- tag--and takes the form Attribute-name="Attribute-value".
--
-- Thus the text between tokens is arbitrary and need not be analysed.
-- In fact the whole text between tags is treated as a token of its
-- own (entities excepted).
-- Inside tags, however, we want to analyse for tag names, attribute
-- names and attribute values.
-- Thus we have to analyse the HTML document after an opening "<" and
-- stop after a closing ">".
--
-- So the idea is the following:
-- We split the syntax into two parts: A text and a tag syntax.
-- The lexer starts with the text syntax, and every time a tag opener
-- or closer is hit, we change the syntax to the appropriate one.
--
-- When defining the syntaxes, the following has to be taken into
-- account:
-- Since the syntax has to contain all token names, unused (and hence
-- in this syntax illegal) names use the Nothing recognizer. In order
-- to return them as Bad_Token, this name has to come first in the
-- sequence of names.
-- Since Document_Type and Comment both use the Bracketed_Comment
-- recognizer with the same opening string "<!", Comment has to come
-- first in the sequence of names.
--
-- If Document_Type is to be analyzed further like other tags, the
-- same trick with switching syntaxes can be applied.
-----------------------------------------------------------------------
function Text_Syntax return Tokenizer.Syntax;
function Tag_Syntax return Tokenizer.Syntax;
-- These must be functions, not constants, because they contain
-- pointers, and we don't have a deep copy defined.
end HTML_Lexer;
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