1 -- filename : type-lam.lua
2 -- comment : Pretty printing of (extended) lambda calculus
3 -- author : Matthijs Kooijman, Universiteit Twente, NL
4 -- copyright: Matthijs Kooijman
7 local utf = unicode.utf8
9 if not buffers then buffers = { } end
10 if not buffers.visualizers then buffers.visualizers = { } end
11 if not buffers.visualizers.lam then buffers.visualizers.lam = { } end
13 buffers.visualizers.lam.colors = {
20 -- Symbols that should have a different representation
21 buffers.visualizers.lam.symbols = {
22 [' '] = {repr = '\\obs '},
23 ['_'] = {repr = '\\_'},
24 ['->'] = {repr = '\\rightarrow'},
25 -- The default * sits very high above the baseline, \ast (u+2217) looks
27 ['*'] = {repr = '\\ast'},
31 -- Keywords that should be bold
32 buffers.visualizers.lam.keywords = {
39 -- See if str starts with a symbol, and return the remaining string and that
40 -- symbol. If no symbol from the table is matched, just returns the first
41 -- character. We can do a lookup directly, since symbols can be different in
42 -- length, so we just loop over all symbols, trying them in turn.
43 function buffers.visualizers.lam.take_symbol(str)
44 for symbol,props in pairs(buffers.visualizers.lam.symbols) do
45 -- Try to remove symbol from the start of str
46 symbol, newstr = utf.match(str, "^(" .. symbol .. ")(.*)")
48 -- Return this tokens repr, or just the token if it has no
50 res = props.repr or symbol
51 -- Enclose the token in {\style .. }
53 res = "{\\" .. props.style .. " " .. res .. "}"
58 -- No symbol found, just return the first character
59 return utf.match(str, "^(.)(.*)")
62 -- Take a single word from str, if posible. Returns the rest of the string and
64 function buffers.visualizers.lam.take_word(str)
65 res, newstr = utf.match(str, "^(%a[%a%d_]+)(.*)")
66 return res, newstr or str
69 -- Tries to match each of the patterns and returns the captures of the first
70 -- matching pattern (up to 5 captures are supported). Returns nil when nothing
72 function buffers.visualizers.lam.match_mul(str, patterns)
73 for i, pat in ipairs(patterns) do
74 a, b, c, d, e = utf.match(str, pat)
82 -- Find any subscripts in the given word and typeset them
83 function buffers.visualizers.lam.do_subscripts(word)
84 local match_mul = buffers.visualizers.lam.match_mul
85 base, sub = match_mul(res, submatches)
87 word = base .. "\\low{" .. sub .. "}"
88 -- After a word has been used as a base, allow subscripts
89 -- without _, even for non-numbers.
90 if not bases[base] then
91 -- Register that we've added this base
93 -- Add a pattern for this base
94 submatches[#submatches+1] = "^(" .. base .. ")([%a%d,]+)$"
100 function buffers.visualizers.lam.begin_of_buffer(type, name)
101 -- Initially allow subscripts using _ or just appending a number (later,
102 -- we will add extra patterns here.
103 submatches = {"^(.*)_([%a%d,]+)$", "^(.*[^%d])(%d+)$"}
104 -- This stores all the bases we've encountered so far (to prevent
105 -- duplicates). For each of them there will be a pattern in submatches
110 function buffers.visualizers.lam.flush_line(str,nested)
111 local result, state = { }, 0
112 local finish, change = buffers.finish_state, buffers.change_state
113 local take_symbol = buffers.visualizers.lam.take_symbol
114 local take_word = buffers.visualizers.lam.take_word
115 local do_subscripts = buffers.visualizers.lam.do_subscripts
116 -- Set the colorscheme, which is used by finish_state and change_state
117 buffers.currentcolors = buffers.visualizers.lam.colors
121 -- See if the next token is a word
122 word, str = take_word(str)
124 if buffers.visualizers.lam.keywords[res] then
125 -- Make all keywords bold
126 word = "{\\bold " .. word .. "}"
128 -- Process any subscripts in the word
129 word = do_subscripts(word)
132 -- The next token is not a word, it must be a symbol
133 symbol, str = take_symbol(str)
136 -- Append the resulting token
137 result[#result+1] = word or symbol
140 state = finish(state, result)
141 buffers.flush_result(result,nested)
144 -- vim: set sw=4 sts=4 expandtab ai: