-- filename : type-lam.lua -- comment : Pretty printing of (extended) lambda calculus -- author : Matthijs Kooijman, Universiteit Twente, NL -- copyright: Matthijs Kooijman -- license : None local utf = unicode.utf8 if not buffers then buffers = { } end if not buffers.visualizers then buffers.visualizers = { } end if not buffers.visualizers.lam then buffers.visualizers.lam = { } end buffers.visualizers.lam.colors = { "prettytwo", "prettyone", "prettythree", "prettyfour" } -- Symbols that should have a different representation buffers.visualizers.lam.symbols = { [' '] = {repr = '\\obs '}, ['_'] = {repr = '\\_'}, ['->'] = {repr = '\\rightarrow'}, -- The default * sits very high above the baseline, \ast (u+2217) looks -- better. ['*'] = {repr = '\\ast'}, } -- Keywords that should be bold buffers.visualizers.lam.keywords = { ['case'] = {}, ['of'] = {}, ['let'] = {}, ['in'] = {}, } -- See if str starts with a symbol, and return the remaining string and that -- symbol. If no symbol from the table is matched, just returns the first -- character. We can do a lookup directly, since symbols can be different in -- length, so we just loop over all symbols, trying them in turn. function buffers.visualizers.lam.take_symbol(str) for symbol,props in pairs(buffers.visualizers.lam.symbols) do -- Try to remove symbol from the start of str symbol, newstr = utf.match(str, "^(" .. symbol .. ")(.*)") if symbol then -- Return this tokens repr, or just the token if it has no -- repr. res = props.repr or symbol -- Enclose the token in {\style .. } if props.style then res = "{\\" .. props.style .. " " .. res .. "}" end return res, newstr end end -- No symbol found, just return the first character return utf.match(str, "^(.)(.*)") end -- Take a single word from str, if posible. Returns the rest of the string and -- the word taken. function buffers.visualizers.lam.take_word(str) res, newstr = utf.match(str, "^(%a[%a%d_]+)(.*)") return res, newstr or str end -- Tries to match each of the patterns and returns the captures of the first -- matching pattern (up to 5 captures are supported). Returns nil when nothing -- matches. function buffers.visualizers.lam.match_mul(str, patterns) for i, pat in ipairs(patterns) do a, b, c, d, e = utf.match(str, pat) if a then return a, b, c, d, e end end return nil end -- Find any subscripts in the given word and typeset them function buffers.visualizers.lam.do_subscripts(word) local match_mul = buffers.visualizers.lam.match_mul base, sub = match_mul(res, submatches) if sub then word = base .. "\\low{" .. sub .. "}" -- After a word has been used as a base, allow subscripts -- without _, even for non-numbers. if not bases[base] then -- Register that we've added this base bases[base] = true -- Add a pattern for this base submatches[#submatches+1] = "^(" .. base .. ")([%a%d,]+)$" end end return word end function buffers.visualizers.lam.begin_of_buffer(type, name) -- Initially allow subscripts using _ or just appending a number (later, -- we will add extra patterns here. submatches = {"^(.*)_([%a%d,]+)$", "^(.*[^%d])(%d+)$"} -- This stores all the bases we've encountered so far (to prevent -- duplicates). For each of them there will be a pattern in submatches -- above. bases = {} end function buffers.visualizers.lam.flush_line(str,nested) local result, state = { }, 0 local finish, change = buffers.finish_state, buffers.change_state local take_symbol = buffers.visualizers.lam.take_symbol local take_word = buffers.visualizers.lam.take_word local do_subscripts = buffers.visualizers.lam.do_subscripts -- Set the colorscheme, which is used by finish_state and change_state buffers.currentcolors = buffers.visualizers.lam.colors while str ~= "" do local found = false local word, symbol -- See if the next token is a word word, str = take_word(str) if word then if buffers.visualizers.lam.keywords[res] then -- Make all keywords bold word = "{\\bold " .. word .. "}" else -- Process any subscripts in the word word = do_subscripts(word) end else -- The next token is not a word, it must be a symbol symbol, str = take_symbol(str) end -- Append the resulting token result[#result+1] = word or symbol end state = finish(state, result) buffers.flush_result(result,nested) end -- vim: set sw=4 sts=4 expandtab ai: