mirror of
https://github.com/koreader/koreader
synced 2024-11-13 19:11:25 +00:00
446 lines
17 KiB
Lua
446 lines
17 KiB
Lua
--[[
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This code was derived from the pico_xml project
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which can be found here:
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http://kd7yhr.org/bushbo/pico_xml.md
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The original C code, written by: Brian O. Bush
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Pure Lua Version written by: William A Adams
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Dramatic Speed Improvements by: Robert G Jakabosky
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https://github.com/Wiladams/LAPHLibs/blob/master/laphlibs/luxl.lua
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References
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http://www.faqs.org/rfcs/rfc3076.html
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http://www.w3.org/TR/REC-xml/
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]]
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local ffi = require "ffi"
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local bit = require "bit"
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local band = bit.band
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--[[
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Types of characters;
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0 is not valid
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1 is letters,
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2 are digits (including '.')
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3 whitespace
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--]]
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local char_type = ffi.new("const int[256]", {
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0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 3, 0, 0, 3, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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});
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-- Internal states that the parser can be in at any given time.
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local ST_START = 0; -- starting base state; default state
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local ST_TEXT =1; -- text state
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local ST_START_TAG = 2; -- start tag state
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local ST_START_TAGNAME =3; -- start tagname state
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local ST_START_TAGNAME_END =4; -- start tagname ending state
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local ST_END_TAG =5; -- end tag state
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local ST_END_TAGNAME=6; -- end tag tagname state
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local ST_END_TAGNAME_END=7; -- end tag tagname ending
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local ST_EMPTY_TAG=8; -- empty tag state
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local ST_SPACE=9; -- linear whitespace state
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local ST_ATTR_NAME=10; -- attribute name state
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local ST_ATTR_NAME_END=11; -- attribute name ending state
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local ST_ATTR_VAL=12; -- attribute value starting state
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local ST_ATTR_VAL2=13; -- attribute value state
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local ST_ERROR=14; -- error state
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-- character classes that we will match against; This could be expanded if
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-- need be, however, we are aiming for simple.
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local CCLASS_NONE = 0; -- matches nothing; a base state
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local CCLASS_LEFT_ANGLE=1; -- matches start tag '<'
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local CCLASS_SLASH=2; -- matches forward slash
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local CCLASS_RIGHT_ANGLE=3; -- matches end tag '>'
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local CCLASS_EQUALS=4; -- matches equals sign
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local CCLASS_QUOTE=5; -- matches double-quotes
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local CCLASS_LETTERS=6; -- matches a-zA-Z letters and digits 0-9
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local CCLASS_SPACE=7; -- matches whitespace
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local CCLASS_ANY=8; -- matches any ASCII character; will match all above classes
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-- Types of events: start element, end element, text, attr name, attr
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-- val and start/end document. Other events can be ignored!
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local EVENT_START = 0; -- Start tag
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local EVENT_END = 1; -- End tag
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local EVENT_TEXT = 2; -- Text
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local EVENT_ATTR_NAME = 3; -- Attribute name
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local EVENT_ATTR_VAL = 4; -- Attribute value
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local EVENT_END_DOC = 5; -- End of document
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local EVENT_MARK = 6; -- Internal only; notes position in buffer
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local EVENT_NONE = 7; -- Internal only; should never see this event
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local entity_refs = {
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["<"] = '<',
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[">"] = '>',
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["&"] = '&',
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["'"] = '\'',
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["""] = '"',
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}
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-- Map constant values to constant names.
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local STATE_NAMES = {
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[ST_START] = "ST_START",
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[ST_TEXT] = "ST_TEXT",
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[ST_START_TAG] = "ST_START_TAG",
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[ST_START_TAGNAME] = "ST_START_TAGNAME",
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[ST_START_TAGNAME_END] = "ST_START_TAGNAME_END",
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[ST_END_TAG] = "ST_END_TAG",
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[ST_END_TAGNAME] = "ST_END_TAGNAME",
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[ST_END_TAGNAME_END] = "ST_END_TAGNAME_END",
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[ST_EMPTY_TAG] = "ST_EMPTY_TAG",
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[ST_SPACE] = "ST_SPACE",
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[ST_ATTR_NAME] = "ST_ATTR_NAME",
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[ST_ATTR_NAME_END] = "ST_ATTR_NAME_END",
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[ST_ATTR_VAL] = "ST_ATTR_VAL",
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[ST_ATTR_VAL2] = "ST_ATTR_VAL2",
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[ST_ERROR] = "ST_ERROR",
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}
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--[[
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State transition table element; contains:
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(1) current state,
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(2) clazz that must match,
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(3) next state if we match, and
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(4) event that is emitted upon match.
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--]]
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-- Note: States must be grouped in match order AND grouped together!
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local LEXER_STATES = {
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-- [0-2] starting state, which also serves as the default state in case of error
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{ state = ST_START, cclass = CCLASS_SPACE, next_state = ST_SPACE, event = EVENT_NONE },
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{ state = ST_START, cclass = CCLASS_LEFT_ANGLE, next_state = ST_START_TAG, event = EVENT_NONE },
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{ state = ST_START, cclass = CCLASS_ANY, next_state = ST_TEXT, event = EVENT_MARK },
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-- [3-5] space state handles linear white space
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{ state = ST_SPACE, cclass = CCLASS_SPACE, next_state = ST_SPACE, event = EVENT_NONE },
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{ state = ST_SPACE, cclass = CCLASS_LEFT_ANGLE, next_state = ST_START_TAG, event = EVENT_TEXT },
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{ state = ST_SPACE, cclass = CCLASS_ANY, next_state = ST_TEXT, event = EVENT_MARK },
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-- [6-8] handle start tag
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{ state = ST_START_TAG, cclass = CCLASS_LETTERS, next_state = ST_START_TAGNAME, event = EVENT_MARK },
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{ state = ST_START_TAG, cclass = CCLASS_SLASH, next_state = ST_END_TAG, event = EVENT_MARK },
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{ state = ST_START_TAG, cclass = CCLASS_SPACE, next_state = ST_START_TAG, event = EVENT_NONE }, -- < tag >
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-- [9-12] handle start tag name
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{ state = ST_START_TAGNAME, cclass = CCLASS_LETTERS, next_state = ST_START_TAGNAME, event = EVENT_NONE },
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{ state = ST_START_TAGNAME, cclass = CCLASS_SPACE, next_state = ST_START_TAGNAME_END, event = EVENT_START },
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{ state = ST_START_TAGNAME, cclass = CCLASS_SLASH, next_state = ST_EMPTY_TAG, event = EVENT_END },
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{ state = ST_START_TAGNAME, cclass = CCLASS_RIGHT_ANGLE, next_state = ST_START, event = EVENT_START },
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-- [13-16] handle start tag name end
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{ state = ST_START_TAGNAME_END, cclass = CCLASS_LETTERS, next_state = ST_ATTR_NAME, event = EVENT_MARK },
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{ state = ST_START_TAGNAME_END, cclass = CCLASS_SPACE, next_state = ST_START_TAGNAME_END, event = EVENT_NONE },
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{ state = ST_START_TAGNAME_END, cclass = CCLASS_RIGHT_ANGLE, next_state = ST_START, event = EVENT_START },
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{ state = ST_START_TAGNAME_END, cclass = CCLASS_SLASH, next_state = ST_EMPTY_TAG, event = EVENT_MARK }, -- Empty tag <br />
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-- [17] handle empty tags, e.g., <br />
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{ state = ST_EMPTY_TAG, cclass = CCLASS_RIGHT_ANGLE, next_state = ST_START, event = EVENT_END }, -- Empty tag <br />
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-- [18] handle end tag, e.g., <tag />
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{ state = ST_END_TAG, cclass = CCLASS_LETTERS, next_state = ST_END_TAGNAME, event = EVENT_NONE },
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-- [19-21] handle end tag name
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{ state = ST_END_TAGNAME, cclass = CCLASS_LETTERS, next_state = ST_END_TAGNAME, event = EVENT_NONE },
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{ state = ST_END_TAGNAME, cclass = CCLASS_RIGHT_ANGLE, next_state = ST_START, event = EVENT_END },
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{ state = ST_END_TAGNAME, cclass = CCLASS_SPACE, next_state = ST_END_TAGNAME_END, event = EVENT_END }, -- space after end tag name </br >
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-- [22-23] handle ending of end tag name
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{ state = ST_END_TAGNAME_END, cclass = CCLASS_SPACE, next_state = ST_END_TAGNAME_END, event = EVENT_NONE },
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{ state = ST_END_TAGNAME_END, cclass = CCLASS_RIGHT_ANGLE,next_state = ST_START, event = EVENT_NONE },
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-- [24-26] handle text
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{ state = ST_TEXT, cclass = CCLASS_SPACE, next_state = ST_SPACE, event = EVENT_NONE },
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{ state = ST_TEXT, cclass = CCLASS_LEFT_ANGLE, next_state = ST_START_TAG, event = EVENT_TEXT },
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{ state = ST_TEXT, cclass = CCLASS_ANY, next_state = ST_TEXT, event = EVENT_NONE },
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-- [27-29] handle attribute names
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{ state = ST_ATTR_NAME, cclass = CCLASS_LETTERS, next_state = ST_ATTR_NAME, event = EVENT_MARK },
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{ state = ST_ATTR_NAME, cclass = CCLASS_SPACE, next_state = ST_ATTR_NAME_END, event = EVENT_ATTR_NAME }, -- space before '=' sign
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{ state = ST_ATTR_NAME, cclass = CCLASS_EQUALS, next_state = ST_ATTR_VAL, event = EVENT_ATTR_NAME }, -- <tag attr ="2">
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-- [30-32] attribute name end
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{ state = ST_ATTR_NAME_END, cclass = CCLASS_SPACE, next_state = ST_ATTR_NAME_END, event = EVENT_NONE },
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{ state = ST_ATTR_NAME_END, cclass = CCLASS_LETTERS, next_state = ST_ATTR_NAME, event = EVENT_MARK },
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{ state = ST_ATTR_NAME_END, cclass = CCLASS_EQUALS, next_state = ST_ATTR_VAL, event = EVENT_NONE },
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-- [33-34] handle attribute values, initial quote and spaces
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{ state = ST_ATTR_VAL, cclass = CCLASS_QUOTE, next_state = ST_ATTR_VAL2, event = EVENT_NONE },
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{ state = ST_ATTR_VAL, cclass = CCLASS_SPACE, next_state = ST_ATTR_VAL, event = EVENT_NONE }, -- initial spaces before quoted attribute value
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-- [35-37] handle actual attribute values
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{ state = ST_ATTR_VAL2, cclass = CCLASS_QUOTE, next_state = ST_START_TAGNAME_END, event = EVENT_ATTR_VAL },
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{ state = ST_ATTR_VAL2, cclass = CCLASS_LETTERS, next_state = ST_ATTR_VAL2, event = EVENT_MARK },
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{ state = ST_ATTR_VAL2, cclass = CCLASS_SLASH, next_state = ST_ATTR_VAL2, event = EVENT_MARK },
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-- [38] End of table marker
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{ state = ST_ERROR, cclass = CCLASS_NONE, next_state = ST_ERROR, event = EVENT_NONE }
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};
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ffi.cdef[[
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struct parse_state {
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const char* buf; /* reference to buffer */
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int bufsz; /* size of buf */
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int mark;
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int i;
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int ix; /* index into buffer */
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};
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]]
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local cclass_match = {
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[CCLASS_LETTERS] = "(ctype == 1 or ctype == 2)",
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[CCLASS_LEFT_ANGLE] = "(c == T_LT)",
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[CCLASS_SLASH] = "(c == T_SLASH)",
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[CCLASS_RIGHT_ANGLE] = "(c == T_GT)",
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[CCLASS_EQUALS] = "(c == T_EQ)",
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[CCLASS_QUOTE] = "(c == T_QUOTE)",
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[CCLASS_SPACE] = "(ctype == 3)",
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[CCLASS_ANY] = "true",
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}
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local STATES = {}
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local STATE_FUNCS = {}
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local function next_char(ps, state, verbose)
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local i = ps.ix
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if i >= ps.bufsz then
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return EVENT_END_DOC, 0, i, state
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end
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ps.i = i
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local c = band(ps.buf[i], 0xff);
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ps.ix = i + 1
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if verbose then
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verbose(i, STATE_FUNCS[state], c)
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end
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-- run state function to find next state.
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return state(ps, c, verbose)
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end
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local fsm_code = ''
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local function code(...)
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for i=1,select("#", ...) do
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fsm_code = fsm_code .. tostring(select(i, ...))
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end
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end
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code[[
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local STATES, next_char, char_type = ...
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local T_LT = string.byte('<')
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local T_SLASH = string.byte('/')
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local T_GT = string.byte('>')
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local T_EQ = string.byte('=')
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local T_QUOTE = string.byte('"')
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]]
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-- pre-define locals for state functions.
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for i=0,#STATE_NAMES do
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local name = STATE_NAMES[i]
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code('local ', name, '_f\n')
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end
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-- group LEXER states.
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for i=1,#LEXER_STATES do
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local p_state = LEXER_STATES[i]
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local state = STATES[p_state.state]
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local cclasses
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if not state then
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cclasses = {}
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state = { state = p_state.state, cclasses = cclasses }
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STATES[p_state.state] = state
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else
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cclasses = state.cclasses
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end
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cclasses[#cclasses + 1] = p_state
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end
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local function gen_cclass_code(prefix, cclass)
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local next_state = STATE_NAMES[cclass.next_state]
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if cclass.event == EVENT_MARK then
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code(prefix, "if(ps.mark == 0) then ps.mark = ps.i end -- mark the position\n")
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elseif cclass.event ~= EVENT_NONE then
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code(prefix, "if(ps.mark > 0) then\n")
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code(prefix,' return ', cclass.event,', ',next_state,'_f\n')
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code(prefix, "end\n")
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end
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code(prefix,'return next_char(ps, ', next_state,'_f, verbose)\n')
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end
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-- generate state functions.
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for i=0,#STATE_NAMES do
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local name = STATE_NAMES[i]
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local state = STATES[i]
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local cclasses = state.cclasses
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code('function ', name, '_f(ps, c, verbose)\n')
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code(' local ctype = char_type[c]\n')
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local has_any
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for i=1,#cclasses do
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local cclass = cclasses[i]
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local id = cclass.cclass
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local condition = cclass_match[id]
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if id == CCLASS_ANY then
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has_any = cclass
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elseif i == 1 then
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code(' if ', condition, ' then\n')
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gen_cclass_code(' ', cclass)
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else
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code(' elseif ', condition, ' then\n')
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gen_cclass_code(' ', cclass)
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end
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end
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code(' end\n')
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-- catch-all for cclass_any or goto error state.
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if has_any then
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gen_cclass_code(' ', has_any)
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else
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-- exit from FSM on error.
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code(' return nil, ',name,'_f, c\n')
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end
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code('end\n')
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-- map state id to state function
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code('STATES[', i, '] = ', name, '_f\n')
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-- reverse map state function to state id
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code('STATES[', name, '_f] = ', i, '\n')
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end
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-- Compile FSM code
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local state_funcs = assert(loadstring(fsm_code, "luxl FSM code"))
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state_funcs(STATE_FUNCS, next_char, char_type)
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fsm_code = nil
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local luxl = {
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EVENT_START = EVENT_START; -- Start tag
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EVENT_END = EVENT_END; -- End tag
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EVENT_TEXT = EVENT_TEXT; -- Text
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EVENT_ATTR_NAME = EVENT_ATTR_NAME; -- Attribute name
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EVENT_ATTR_VAL = EVENT_ATTR_VAL; -- Attribute value
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EVENT_END_DOC = EVENT_END_DOC; -- End of document
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EVENT_MARK = EVENT_MARK; -- Internal only; notes position in buffer
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EVENT_NONE = EVENT_NONE; -- Internal only; should never see this event
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}
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local luxl_mt = { __index = luxl }
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function luxl.new(buffer, bufflen)
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local newone = {
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buf = ffi.cast("const uint8_t *", buffer); -- pointer to "uint8_t *" buffer (0 based)
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bufsz = bufflen; -- size of input buffer
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state = ST_START; -- current state
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event = EVENT_NONE; -- current event
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err = 0; -- number of errors thus far
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markix = 0; -- offset of current item of interest
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marksz = 0; -- size of current item of interest
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MsgHandler = nil; -- Routine to handle messages
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ErrHandler = nil; -- Routine to call when there's an error
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EventHandler = nil;
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ps = ffi.new('struct parse_state', {
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buf = buffer,
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bufsz = bufflen,
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mark = 0,
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i = 0,
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ix = 0,
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}),
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}
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setmetatable(newone, luxl_mt);
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return newone;
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end
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function luxl:Reset(buffer, bufflen)
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self.buf = buffer -- pointer to "uint8_t *" buffer (0 based)
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self.bufsz = bufflen -- size of input buffer
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self.state = ST_START -- current state
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self.event = EVENT_NONE -- current event
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self.err = 0 -- number of errors thus far
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self.markix = 0 -- offset of current item of interest
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self.marksz = 0 -- size of current item of interest
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local ps = self.ps
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ps.buf = buffer
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ps.bufsz = bufflen
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ps.mark = 0
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ps.i = 0
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ps.ix = 0
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end
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function luxl:SetMessageHandler(handler)
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self.MsgHandler = handler;
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end
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--[[
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GetNext is responsible for moving through the stream
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of characters. At the moment, it's fairly naive in
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terms of character encodings.
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In a more robust implementation, luxl will read from a
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stream, which knows about the specific encoding, and
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will hand out code points based on that particular encoding.
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So, only straight ASCII for the moment.
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Returns event type, starting offset, size
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--]]
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function luxl:GetNext()
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local event, state_f, c
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local ps = self.ps
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ps.mark = 0
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state_f = STATE_FUNCS[self.state]
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repeat
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event, state_f, c = next_char(ps, state_f, self.MsgHandler)
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-- update state id.
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self.state = STATE_FUNCS[state_f]
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if not event then
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-- handle error
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-- default to start state
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self.err = self.err + 1;
|
|
if self.ErrHandler then
|
|
self.ErrHandler(ps.i, self.state, c);
|
|
end
|
|
end
|
|
until event
|
|
-- basically we are guaranteed never to have an event of
|
|
-- type EVENT_MARK or EVENT_NONE here.
|
|
self.event = event
|
|
local markix = ps.mark
|
|
local marksz = ps.i-ps.mark
|
|
self.markix = markix
|
|
self.marksz = marksz
|
|
if(self.EventHandler) then
|
|
self.EventHandler(event, markix, marksz)
|
|
end
|
|
return event, markix, marksz
|
|
end
|
|
|
|
function luxl:Lexemes()
|
|
return function()
|
|
local event, offset, size = self:GetNext();
|
|
if(event == EVENT_END_DOC) then
|
|
return nil;
|
|
else
|
|
return event, offset, size;
|
|
end
|
|
end
|
|
end
|
|
|
|
return luxl
|