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 buffers.visualizers.lam.symbols = {
21 [' '] = {repr = '\\obs '},
22 ['_'] = {repr = '\\_'},
23 ['->'] = {repr = '\\rightarrow'},
24 -- The default * sits very high above the baseline, \ast (u+2217) looks
26 ['*'] = {repr = '\\ast'},
29 buffers.visualizers.lam.keywords = {
37 function buffers.visualizers.lam.take_symbol(str)
38 -- See if str starts with a symbol, and return the remaining
39 -- string and that symbol. If no symbol from the table is matched,
40 -- just returns the first character.
41 -- 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 for symbol,props in pairs(buffers.visualizers.lam.symbols) do
44 -- Try to remove symbol from the start of str
45 symbol, newstr = utf.match(str, "^(" .. symbol .. ")(.*)")
47 -- Return this tokens repr, or just the token if it has no
49 res = props.repr or symbol
50 -- Enclose the token in {\style .. }
52 res = "{\\" .. props.style .. " " .. res .. "}"
57 -- No symbol found, just return the first character
58 return utf.match(str, "^(.)(.*)")
61 -- Take a single word from str, if posible. Returns the rest of the string and
63 function buffers.visualizers.lam.take_word(str)
64 res, newstr = utf.match(str, "^(%a[%a%d_]+)(.*)")
65 return res, newstr or str
68 -- Tries to match each of the patterns and returns the captures of the first
69 -- matching pattern (up to 5 captures are supported). Returns nil when nothing
71 function buffers.visualizers.lam.match_mul(str, patterns)
72 for i, pat in ipairs(patterns) do
73 a, b, c, d, e = utf.match(str, pat)
81 function buffers.visualizers.lam.begin_of_buffer()
82 -- Initially allow subscripts using _ or just appending a number (later,
83 -- we will add extra patterns here.
84 submatches = {"^(.*)_([%a%d,]+)$", "^(.*[^%d])(%d+)$"}
85 -- This stores all the bases we've encountered so far (to prevent
86 -- duplicates). For each of them there will be a pattern in submatches
91 function buffers.visualizers.lam.end_of_buffer()
92 -- Reset submatches and bases, since flush_line can be called without
93 -- begin / end_of_buffer for \type.
94 buffers.visualizers.lam.begin_of_buffer()
98 function buffers.visualizers.lam.do_subscripts(word)
99 local match_mul = buffers.visualizers.lam.match_mul
100 base, sub = match_mul(res, submatches)
102 word = base .. "\\low{" .. sub .. "}"
103 -- After a word has been used as a base, allow subscripts
104 -- without _, even for non-numbers.
105 if bases and not bases[base] then
106 -- Register that we've added this base
108 -- Add a pattern for this base
109 submatches[#submatches+1] = "^(" .. base .. ")([%a%d,]+)$"
115 function buffers.visualizers.lam.flush_line(str,nested)
116 local result, state = { }, 0
117 local finish, change = buffers.finish_state, buffers.change_state
118 local take_symbol = buffers.visualizers.lam.take_symbol
119 local take_word = buffers.visualizers.lam.take_word
120 local do_subscripts = buffers.visualizers.lam.do_subscripts
121 -- Set the colorscheme, which is used by finish_state and change_state
122 buffers.currentcolors = buffers.visualizers.lam.colors
126 -- See if the next token is a word
127 word, str = take_word(str)
129 if buffers.visualizers.lam.keywords[res] then
130 -- Make all keywords bold
131 word = "{\\bold " .. word .. "}"
133 -- Process any subscripts in the word
134 word = do_subscripts(word)
137 -- The next token is not a word, it must be a symbol
138 symbol, str = take_symbol(str)
141 -- Append the resulting token
142 result[#result+1] = word or symbol
145 state = finish(state, result)
146 buffers.flush_result(result,nested)
149 -- Call end_of_buffer once to set up submatches (since \type doesn't call
150 -- begin_of_buffer / end_of_buffer).
151 buffers.visualizers.lam.end_of_buffer()
153 -- vim: set sw=4 sts=4 expandtab ai: