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 local vis = buffers.newvisualizer("lam")
18 -- Symbols that should have a different representation
20 [' '] = {repr = '\\obs '},
21 ['_'] = {repr = '\\_'},
22 ['->'] = {repr = '\\rightarrow'},
23 -- The default * sits very high above the baseline, \ast (u+2217) looks
25 ['*'] = {repr = '\\ast'},
26 ['~'] = {repr = '\\sim'},
27 ['|'] = {repr = '\\char' .. utf.byte('|')},
30 -- Keywords that should be bold
41 -- Store the last line for each indent level
42 local indentlines = {}
44 -- See if str starts with a symbol, and return the remaining string and that
45 -- symbol. If no symbol from the table is matched, just returns the first
46 -- character. We can do a lookup directly, since symbols can be different in
47 -- length, so we just loop over all symbols, trying them in turn.
48 local function take_symbol(str)
49 for symbol,props in pairs(symbols) do
50 -- Try to remove symbol from the start of str
51 symbol, newstr = utf.match(str, "^(" .. symbol .. ")(.*)")
53 -- Return this tokens repr, or just the token if it has no
55 res = props.repr or symbol
56 -- Enclose the token in {\style .. }
58 res = "{\\" .. props.style .. " " .. res .. "}"
63 -- No symbol found, just return the first character
64 return utf.match(str, "^(.)(.*)")
67 -- Take a single word from str, if posible. Returns the rest of the string and
69 local function take_word(str)
70 -- A word must always start with a-z (in particular, λ is not a valid
72 res, newstr = utf.match(str, "^([a-zA-Z][%a%d%+%-%,_]+)(.*)")
73 return res, newstr or str
76 -- Tries to match each of the patterns and returns the captures of the first
77 -- matching pattern (up to 5 captures are supported). Returns nil when nothing
79 local function match_mul(str, patterns)
80 for i, pat in ipairs(patterns) do
81 a, b, c, d, e = utf.match(str, pat)
89 -- Find any subscripts in the given word and typeset them
90 local function do_subscripts(word)
91 base, sub = match_mul(res, submatches)
93 word = base .. "\\low{" .. sub .. "}"
94 -- After a word has been used as a base, allow subscripts
95 -- without _, even for non-numbers.
96 if not bases[base] then
97 -- Register that we've added this base
99 -- Add a patterns for this base. First, the base with a single
100 -- letter or number subscript.
101 submatches[#submatches+1] = "^(" .. base .. ")([%a%d])$"
102 -- Seconde, the base with a longer prefix that includes at least
103 -- one of +-, (to catch things like ri+1, but not return).
104 submatches[#submatches+1] = "^(" .. base .. ")([%a%d]*[%-%+%,]+[%a%d%-%+%,]*)$"
110 -- Do proper aligning for subsequent lines. For example, in
113 -- We replace the spaces in the second line with a skip with the same with as
114 -- "foo ", to align the | with the =.
115 -- For this, we keep a table "indentlines", which contains all previous lines
116 -- with smaller indent levels that are still "in scope" (e.g., have not yet
117 -- been followed by a line with a smaller indent level). For example:
123 -- After the last line, the table will contain:
124 -- { 0 = "line1", 2 = " line4", 4 = " line5"}
125 -- In other words, line3 is no longer in scope since it is "hidden" by
126 -- line4, and line is no longer in scope since it is replaced by line4.
127 local function do_indent(line)
128 newind, rest = utf.match(line, '^(%s*)(.*)')
130 -- Loop all the previous lines
131 for indent, unused in pairs(indentlines) do
132 if indent > #newind then
133 -- Remove any lines with a larger indent
134 indentlines[indent] = nil
135 elseif indent < #newind and indent > prev then
136 -- Find the last line (e.g, with the highest indent) with an
137 -- indent smaller than the new indent. This is the line from which
138 -- we need to copy the indent.
143 -- Always store this line, possibly overwriting a previous line with the
145 indentlines[#newind] = line
148 -- If there is a previous line with a smaller indent, make sure we
149 -- align with it. We do this by taking a prefix from that previous
150 -- line just as long as our indent. This gives us a bunch of
151 -- whitespace, with a few non-whitespace characters. We find out the
152 -- width of this prefix, and put whitespace just as wide as that
153 -- prefix before the current line, instead of the whitespace
154 -- characters that were there.
155 -- Doing this is slightly risky, since the prefix might contain
156 -- unfinished markup (e.g., \foo{bar without the closing }). We might
157 -- need to solve this later.
158 copyind = utf.sub(indentlines[prev], 1, #newind)
159 setwidth = "\\setwidthof{" .. copyind .. "}\\to\\pretlamalignwidth"
160 hskip = "\\hskip\\pretlamalignwidth"
161 return "{" .. setwidth .. hskip .. "}" .. rest
163 -- No previous line? Just return the unmodified line then
168 -- Mark the begin of a block of lambda formatted buffers or expressions. This
169 -- means that, until you call end_of_block again, the subscript bases are
170 -- shared. For example, if you have \lam{y1} some text \lam{yn} within a
171 -- single block, the yn will properly get subscripted. Be sure to call
172 -- end_of_block again!
174 -- Blocks can be partially nested, meaning that the block
175 -- won't be closed until end_of_block was called exactly as often as
176 -- begin_of_block. However, subscripts from the inner block can still
177 -- influence subscripts in the outer block.
178 function vis.begin_of_block()
179 vis.begin_of_display()
180 in_block = in_block + 1
183 -- Ends the current block
184 function vis.end_of_block()
185 in_block = in_block - 1
188 function vis.begin_of_display()
189 if in_block == 0 then
190 -- Initially allow subscripts using _ or just appending a number (later,
191 -- we will add extra patterns here.
192 submatches = {"^(%a*)_([%a%d,]+)$", "^(%a+)(%d+)$"}
193 -- This stores all the bases we've encountered so far (to prevent
194 -- duplicates). For each of them there will be a pattern in submatches
202 -- Make things work for inline typeing (e.g., \type{}) as well.
203 vis.begin_of_inline = vis.begin_of_display
204 vis.end_of_inline = vis.end_of_display
206 function vis.flush_line(str,nested)
207 local result, state = { }, 0
208 local finish, change = buffers.finish_state, buffers.change_state
210 -- Set the colorscheme, which is used by finish_state and change_state
211 buffers.currentcolors = colors
215 -- See if the next token is a word
216 word, str = take_word(str)
218 if keywords[res] then
219 -- Make all keywords bold
220 word = "{\\bold " .. word .. "}"
222 -- Process any subscripts in the word
223 word = do_subscripts(word)
226 -- The next token is not a word, it must be a symbol
227 symbol, str = take_symbol(str)
230 -- Append the resulting token
231 result[#result+1] = word or symbol
234 state = finish(state, result)
235 buffers.flush_result(result,nested)
238 -- vim: set sw=4 sts=4 expandtab ai: