372 lines
10 KiB
Lua
372 lines
10 KiB
Lua
require("helper")
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-- CLASS DEFINITIONS
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-- A stream of text (kind of)
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-- with some helping methods
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Reader = class("Reader")
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-- Construct a reader from
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function Reader:new(text)
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assert_type("string")(text,"Arg 'text' #1: %s")
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self.text = text
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end
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-- Get the substring of the readers text in a bounds
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function Reader:get(first,final)
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assert_type("number")(first,"Arg 'first' #1: %s")
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assert_type("number","nil")(final,"Arg 'final' #2: %s")
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return self.text:sub(first,final)
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end
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-- Match on the reader's text from an index
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function Reader:find(pattern,init)
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assert_type("string")(pattern,"Arg 'pattern' #1: %s")
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assert_type("number","nil")(init,"Arg 'init' #2: %s")
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return self.text:find(pattern,init)
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end
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function Reader:match(pattern,init)
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assert_type("string")(pattern,"Arg 'pattern' #1: %s")
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assert_type("number")(init,"Arg 'init' #2: %s")
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return self.text:match(pattern,init)
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end
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-- A range of text being considered
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-- like a cursor
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Range = class("Range")
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-- Construct a range of text from a reader and bounds
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function Range:new(reader,first,final)
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assert_meta(Reader)(reader)
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assert_type("number","nil")(first,"Arg 'first' #1: %s")
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assert_type("number","nil")(final,"Arg 'final' #2: %s")
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self.reader = reader
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self.first = first
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self.final = final
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end
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function Range:text()
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return self.reader:get(self.first or 1,self.final)
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end
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function Range:find(pattern)
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return self.reader:find(pattern,self.first)
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end
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function Range:move(first,final)
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assert_type("number","nil")(first,"Arg 'first' #1: %s")
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assert_type("number","nil")(final,"Arg 'final' #2: %s")
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self.first = first
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self.final = final
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-- note that this function returns itself
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return self
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end
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Expression = class("Expression")
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-- Construct an expression from items (or not)
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function Expression:new(items)
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items = items or {}
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assert_type("table")(items)
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self.items = {}
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for item in iterate(items) do
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self:insert(item)
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end
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end
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function Expression:empty()
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return #self.items == 0
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end
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-- insert a word or sub expression into this one
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function Expression:insert(...)
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-- closures for nvim highlighting
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local function insert_word(word)
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-- Whitespace might confuse bindings, remove them
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local cleaned = word:match("^%s*(.-)%s*$")
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if cleaned ~= "" then
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table.insert(self.items,cleaned)
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end
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end
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local function insert_expression(expr)
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assert_meta(expr,Expression)
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table.insert(self.items,expr)
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end
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for item in iterate({...}) do
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case_of({
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table = function(expr)
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insert_expression(expr)
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end,
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string = function(word)
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insert_word(word)
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end
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})(type(item),item)
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end
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end
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function Expression:string()
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local parts = {}
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for index,item in pairs(self.items) do
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parts[index] = tostring(item)
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end
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return string.format("(%s)",table.concat(parts," "))
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end
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function Expression:abstract(infer)
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local parts = {}
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local count = 0
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for index,item in pairs(self.items) do
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parts[index] = case_of({
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[Expression] = function(item)
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local text
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if infer then
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text = item:text()
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if not text then
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count = count + 1
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text = tostring(count)
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end
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else
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text = "..."
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end
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return Expression({text})
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end,
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string = id
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})(type_of(item),item)
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end
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return Expression(parts)
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end
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function Expression:text()
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-- Get the text
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local text = self.items[#self.items]
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-- Ensure that the subexpression is valid abstract
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if type(text) ~= "string" then return end
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return text
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end
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function Expression:locate(str,uri)
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self.location = str
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self.source = uri
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return self
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end
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function Expression:link(msg)
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return string.format(
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"in '%s' @%s (%s)",
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msg,
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tostring(self),
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tostring(self.location or "?"),
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tostring(self.source or "?.nel")
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)
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end
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Consumer = class("Consumer")
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function Consumer:new(content)
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self.range = Range(Reader(content))
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self.col = 1
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self.row = 1
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end
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function Consumer:remaining()
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return self.range:text()
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end
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function Consumer:mark()
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end
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-- From a table of actions of patterns,
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-- consume the earliest pattern (index)
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-- and call the value
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function Consumer:consume(t)
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-- t: {string = function...}
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assert_type("table")(t,"Arg 't' #1: %s")
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if not next(t) then
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error("The match table cannot be empty!",2)
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end
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for index,func in pairs(t) do
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assert_type("string")(index,"Bad 't' index: %s")
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assert_type("function")(func,"Bad 't' item: %s")
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end
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local origin = self.range.first or 1
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-- Get the next earliest match
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local findex,ffinal,fpattern,ffunc,fexcess
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for pattern,new_func in pairs(t) do
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local new_index,new_final = self.range:find(pattern)
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if new_index and
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((not findex) or (findex > new_index))
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then
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if not new_index then return end
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findex = new_index
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ffinal = new_final
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fpattern = pattern
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ffunc = new_func
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fexcess = self.range.reader:get(
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self.range.first or 1,
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new_final - 1
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)
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end
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end
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-- Pass into the func
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if not ffunc then
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return nil
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end
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assert(findex) assert(ffinal)
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self.range:move(ffinal+1) -- Move range to after the match
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local fmatch = self.range.reader:match(fpattern,findex)
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-- Pass back consumed result to
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local sum = self.range.reader:get(origin+1,self.range.first)
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:gsub("\r\n","\n")
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:gsub("\r","\n")
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for char in sum:gmatch(".") do
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if char == "\n" then
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self.row = self.row + 1
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self.col = 1
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else
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self.col = self.col + 1
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end
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end
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return ffunc(fexcess,fmatch)
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end
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Binding = class("Binding")
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-- Construct from a neli string to infer a binding
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-- note that you must wrap this definition in "(<def>)"!
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function Binding:new(expression,callback)
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assert_meta(Expression)(expression,"Arg 'expression' #1: %s")
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if type_of(callback) == "function" then
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self.callback = callback
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else
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self.value = callback
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end
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self.template = expression:abstract(true)
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end
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function Binding:string()
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return string.format("Binding %s: %s",self.template,tostring(self.value or self.callback))
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end
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function Binding:call(s,e,c)
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assert_meta(Scope)(s)
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assert_meta(Chain)(c)
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return self.value or self.callback(s,e,c)
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end
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function Binding:check(expression)
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assert_meta(Expression)(expression,"Arg 'expression' #1: %s")
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local candid = expression:abstract()
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local data = {}
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local index
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local loop = true
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if #candid.items ~= #self.template.items then
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return false
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end
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while loop do
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local old = index
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index,template_item = next(self.template.items,old)
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index,candid_item = next(candid.items,old)
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local result = case_of({
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[Expression] = function()
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-- item is not an expression, cannot bind
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if type_of(candid_item) ~= Expression then
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loop = false
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else
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data[template_item:text()] = expression.items[index]
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end
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end,
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string = function()
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-- words don't match, cannot bind
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if candid_item ~= template_item then
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loop = false
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end
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end,
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["nil"] = function()
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-- base case where both expressions terminate together
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if not candid_item then
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return data
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end
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end
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})(type_of(template_item))
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if result then return result end
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end
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end
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Chain = class("Chain")
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function Chain:new(data)
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assert_type("string")(data,"Arg 'data' #1: %s")
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self.data = data
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end
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function Chain:from(previous)
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assert_meta(Chain)(previous,"Arg 'previous' #1: %s")
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previous.next = self
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self.previous = previous
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return self
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end
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function Chain:string()
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return string.format("Chain:%s",table.concat(self:flatten(),", "))
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end
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function Chain:flatten(tab)
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tab = tab or {}
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if self.next then
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self.next:flatten(tab)
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end
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table.insert(tab,self.data)
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return tab
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end
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-- The scope of a neli expression under evaluation
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-- without exact faith to traditional language scopes
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Scope = class("Scope")
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function Scope:new(bindings)
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self.bindings = {}
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for binding in iterate(bindings or {}) do
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self:insert(binding)
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end
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end
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function Scope:string()
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return string.format("Scope: {\n\t%s\n}",table.concat(map(self.bindings,tostring),"\n\t"))
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end
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function Scope:insert(binding)
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assert_meta(Binding)(binding,"Arg 'binding' #1: %s")
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for competitor in iterate(self.bindings) do
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if competitor:check(binding.template) then
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nerror("Conflicting sibling bindings in scope.")
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end
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end
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table.insert(self.bindings,binding)
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end
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function Scope:run(expression,chain,original)
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original = original or self
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assert_meta(Expression)(expression,"Arg 'expression' #1: %s")
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assert_meta(Chain)(chain,"Arg 'chain' #2: %s")
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-- Could be multiple bindings so make a table
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local binds = {}
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for binding in iterate(self.bindings) do
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local bind = binding:check(expression)
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-- Insert into table
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if bind then binds[binding] = bind end
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end
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local binding,bind = next(binds)
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-- Check for multiple
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if not bind then
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if self.parent then
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return self.parent:run(expression,chain,self)
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else
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local extra = ""
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if #expression.items == 1 then
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local item = expression.items[1]
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if type_of(item) == Expression then
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extra = extra .. "\nNote: This expression is formed (just bracketed) of another single expression. Maybe too many brackets were used here?"
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else
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extra = extra .. "\n\tNote: This is a 'text' expression, it has no subexpressions. It is most likely that an expected object definition was not bound to the scope or there is a typo."
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end
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end
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error(
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string.format(
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"nel: No binding for '%s' in scope.",
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tostring(expression:abstract()),
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extra
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),3
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)
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end
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-- Should never happen!
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elseif next(binds,binding) then
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local candidates = {}
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for binding,bind in pairs(binds) do
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table.insert(candidates,tostring(binding.template))
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end
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error(
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string.format(
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"nel: Ambiguous bindings in scope for '%s': %s",
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tostring(expression:abstract()),
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table.concat(candidates)
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)
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,2)
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else
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return binding:call(
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original,
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bind,
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chain
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)
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end
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end
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return _G
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