lite-xl/data/core/tokenizer.lua

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local syntax = require "core.syntax"
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local tokenizer = {}
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local function push_token(t, type, text)
local prev_type = t[#t-1]
local prev_text = t[#t]
if prev_type and (prev_type == type or prev_text:find("^%s*$")) then
t[#t-1] = type
t[#t] = prev_text .. text
else
table.insert(t, type)
table.insert(t, text)
end
end
local function push_tokens(t, syn, pattern, full_text, find_results)
if #find_results > 2 then
-- We do some manipulation with find_results so that it's arranged
-- like this:
-- { start, end, i_1, i_2, i_3, …, i_last }
-- Each position spans characters from i_n to ((i_n+1) - 1), to form
-- consecutive spans of text.
--
-- If i_1 is not equal to start, start is automatically inserted at
-- that index.
if find_results[3] ~= find_results[1] then
table.insert(find_results, 3, find_results[1])
end
-- Copy the ending index to the end of the table, so that an ending index
-- always follows a starting index after position 3 in the table.
table.insert(find_results, find_results[2] + 1)
-- Then, we just iterate over our modified table.
for i = 3, #find_results - 1 do
local start = find_results[i]
local fin = find_results[i + 1] - 1
local type = pattern.type[i - 2]
-- ↑ (i - 2) to convert from [3; n] to [1; n]
local text = full_text:sub(start, fin)
push_token(t, syn.symbols[text] or type, text)
end
else
local start, fin = find_results[1], find_results[2]
local text = full_text:sub(start, fin)
push_token(t, syn.symbols[text] or pattern.type, text)
end
end
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local function is_escaped(text, idx, esc)
local byte = esc:byte()
local count = 0
for i = idx - 1, 1, -1 do
if text:byte(i) ~= byte then break end
count = count + 1
end
return count % 2 == 1
end
local function find_non_escaped(text, pattern, offset, esc)
while true do
local s, e = text:find(pattern, offset)
if not s then break end
if esc and is_escaped(text, s, esc) then
offset = e + 1
else
return s, e
end
end
end
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-- State is a 32-bit number that is four separate bytes, illustrating how many
-- differnet delimiters we have open, and which subsyntaxes we have active.
-- At most, there are 3 subsyntaxes active at the same time. Beyond that,
-- does not support further highlighting.
-- You can think of it as a maximum 4 integer (0-255) stack. It always has
-- 1 integer in it. Calling `push_subsyntax` increases the stack depth. Calling
-- `pop_subsyntax` decreases it. The integers represent the index of a pattern
-- that we're following in the syntax. The top of the stack can be any valid
-- pattern index, any integer lower in the stack must represent a pattern that
-- specifies a subsyntax.
-- If you do not have subsyntaxes in your syntax, the three most
-- singificant numbers will always be 0, the stack will only ever be length 1
-- and the state variable will only ever range from 0-255.
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local function retrieve_syntax_state(incoming_syntax, state)
local current_syntax, subsyntax_info, current_pattern_idx, current_level =
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incoming_syntax, nil, state, 0
if state > 0 and (state > 255 or current_syntax.patterns[state].syntax) then
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-- If we have higher bits, then decode them one at a time, and find which
-- syntax we're using. Rather than walking the bytes, and calling into
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-- `syntax` each time, we could probably cache this in a single table.
for i = 0, 2 do
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local target = bit32.extract(state, i*8, 8)
if target ~= 0 then
if current_syntax.patterns[target].syntax then
subsyntax_info = current_syntax.patterns[target]
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current_syntax = type(subsyntax_info.syntax) == "table" and
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subsyntax_info.syntax or syntax.get(subsyntax_info.syntax)
current_pattern_idx = 0
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current_level = i+1
else
current_pattern_idx = target
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break
end
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else
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break
end
end
end
return current_syntax, subsyntax_info, current_pattern_idx, current_level
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end
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function tokenizer.tokenize(incoming_syntax, text, state)
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local res = {}
local i = 1
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if #incoming_syntax.patterns == 0 then
return { "normal", text }
end
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state = state or 0
-- incoming_syntax : the parent syntax of the file.
-- state : a 32-bit number representing syntax state (see above)
-- current_syntax : the syntax we're currently in.
-- subsyntax_info : info about the delimiters of this subsyntax.
-- current_pattern_idx: the index of the pattern we're on for this syntax.
-- current_level : how many subsyntaxes deep we are.
local current_syntax, subsyntax_info, current_pattern_idx, current_level =
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retrieve_syntax_state(incoming_syntax, state)
-- Should be used to set the state variable. Don't modify it directly.
local function set_subsyntax_pattern_idx(pattern_idx)
current_pattern_idx = pattern_idx
state = bit32.replace(state, pattern_idx, current_level*8, 8)
end
local function push_subsyntax(entering_syntax, pattern_idx)
set_subsyntax_pattern_idx(pattern_idx)
current_level = current_level + 1
subsyntax_info = entering_syntax
current_syntax = type(entering_syntax.syntax) == "table" and
entering_syntax.syntax or syntax.get(entering_syntax.syntax)
current_pattern_idx = 0
end
local function pop_subsyntax()
set_subsyntax_pattern_idx(0)
current_level = current_level - 1
set_subsyntax_pattern_idx(0)
current_syntax, subsyntax_info, current_pattern_idx, current_level =
retrieve_syntax_state(incoming_syntax, state)
end
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while i <= #text do
-- continue trying to match the end pattern of a pair if we have a state set
if current_pattern_idx > 0 then
local p = current_syntax.patterns[current_pattern_idx]
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local s, e = find_non_escaped(text, p.pattern[2], i, p.pattern[3])
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local cont = true
-- If we're in subsyntax mode, always check to see if we end our syntax
-- first, before the found delimeter, as ending the subsyntax takes
-- precedence over ending the delimiter in the subsyntax.
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if subsyntax_info then
local ss, se = find_non_escaped(
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text,
subsyntax_info.pattern[2],
i,
subsyntax_info.pattern[3]
)
-- If we find that we end the subsyntax before the
-- delimiter, push the token, and signal we shouldn't
-- treat the bit after as a token to be normally parsed
-- (as it's the syntax delimiter).
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if ss and (s == nil or ss < s) then
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push_token(res, p.type, text:sub(i, ss - 1))
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i = ss
cont = false
end
end
-- If we don't have any concerns about syntax delimiters,
-- continue on as normal.
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if cont then
if s then
push_token(res, p.type, text:sub(i, e))
set_subsyntax_pattern_idx(0)
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i = e + 1
else
push_token(res, p.type, text:sub(i))
break
end
end
end
-- General end of syntax check. Applies in the case where
-- we're ending early in the middle of a delimiter, or
-- just normally, upon finding a token.
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if subsyntax_info then
local s, e = find_non_escaped(
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text,
"^" .. subsyntax_info.pattern[2],
i,
nil
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)
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if s then
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push_token(res, subsyntax_info.type, text:sub(i, e))
-- On finding unescaped delimiter, pop it.
pop_subsyntax()
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i = e + 1
end
end
-- find matching pattern
local matched = false
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for n, p in ipairs(current_syntax.patterns) do
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local pattern = (type(p.pattern) == "table") and p.pattern[1] or p.pattern
local find_results = { text:find("^" .. pattern, i) }
local start, fin = find_results[1], find_results[2]
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if start then
-- matched pattern; make and add tokens
push_tokens(res, current_syntax, p, text, find_results)
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-- update state if this was a start|end pattern pair
if type(p.pattern) == "table" then
-- If we have a subsyntax, push that onto the subsyntax stack.
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if p.syntax then
push_subsyntax(p, n)
else
set_subsyntax_pattern_idx(n)
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end
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end
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-- move cursor past this token
i = fin + 1
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matched = true
break
end
end
-- consume character if we didn't match
if not matched then
push_token(res, "normal", text:sub(i, i))
i = i + 1
end
end
return res, state
end
local function iter(t, i)
i = i + 2
local type, text = t[i], t[i+1]
if type then
return i, type, text
end
end
function tokenizer.each_token(t)
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return iter, t, -1
end
return tokenizer