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 = '\\HDLine[width=.20 * \\the\\textwidth]'},
27 ['|'] = {repr = '\\char' .. utf.byte('|')},
28 ['$'] = {repr = '\\char' .. utf.byte('$')},
31 -- Keywords that should be bold
45 -- Store the last line for each indent level
46 local indentlines = {}
48 -- See if str starts with a symbol, and return the remaining string and that
49 -- symbol. If no symbol from the table is matched, just returns the first
50 -- character. We can do a lookup directly, since symbols can be different in
51 -- length, so we just loop over all symbols, trying them in turn.
52 local function take_symbol(str)
53 for symbol,props in pairs(symbols) do
54 -- Try to remove symbol from the start of str
55 symbol, newstr = utf.match(str, "^(" .. symbol .. ")(.*)")
57 -- Return this tokens repr, or just the token if it has no
59 res = props.repr or symbol
60 -- Enclose the token in {\style .. }
62 res = "{\\" .. props.style .. " " .. res .. "}"
67 -- No symbol found, just return the first character
68 return utf.match(str, "^(.)(.*)")
71 -- Take a single word from str, if posible. Returns the rest of the string and
73 local function take_word(str)
74 -- A word must always start with a-z (in particular, λ is not a valid
76 res, newstr = utf.match(str, "^([a-zA-Z][%a%d%+%-%,_]+)(.*)")
77 return res, newstr or str
80 -- Tries to match each of the patterns and returns the captures of the first
81 -- matching pattern (up to 5 captures are supported). Returns nil when nothing
83 local function match_mul(str, patterns)
84 for i, pat in ipairs(patterns) do
85 a, b, c, d, e = utf.match(str, pat)
93 -- Find any subscripts in the given word and typeset them
94 local function do_subscripts(word)
95 base, sub = match_mul(res, submatches)
97 word = base .. "\\low{" .. sub .. "}"
98 -- After a word has been used as a base, allow subscripts
99 -- without _, even for non-numbers.
100 if not bases[base] then
101 -- Register that we've added this base
103 -- Add a patterns for this base. First, the base with a single
104 -- letter or number subscript.
105 submatches[#submatches+1] = "^(" .. base .. ")([%a%d])$"
106 -- Seconde, the base with a longer prefix that includes at least
107 -- one of +-, (to catch things like ri+1, but not return).
108 submatches[#submatches+1] = "^(" .. base .. ")([%a%d]*[%-%+%,]+[%a%d%-%+%,]*)$"
114 -- Do proper aligning for subsequent lines. For example, in
117 -- We replace the spaces in the second line with a skip with the same with as
118 -- "foo ", to align the | with the =.
119 -- For this, we keep a table "indentlines", which contains all previous lines
120 -- with smaller indent levels that are still "in scope" (e.g., have not yet
121 -- been followed by a line with a smaller indent level). For example:
127 -- After the last line, the table will contain:
128 -- { 0 = "line1", 2 = " line4", 4 = " line5"}
129 -- In other words, line3 is no longer in scope since it is "hidden" by
130 -- line4, and line is no longer in scope since it is replaced by line4.
131 local function do_indent(line)
132 newind, rest = utf.match(line, '^(%s*)(.*)')
134 -- Loop all the previous lines
135 for indent, unused in pairs(indentlines) do
136 if indent > #newind then
137 -- Remove any lines with a larger indent
138 indentlines[indent] = nil
139 elseif indent < #newind and indent > prev then
140 -- Find the last line (e.g, with the highest indent) with an
141 -- indent smaller than the new indent. This is the line from which
142 -- we need to copy the indent.
147 -- Always store this line, possibly overwriting a previous line with the
149 indentlines[#newind] = line
152 -- If there is a previous line with a smaller indent, make sure we
153 -- align with it. We do this by taking a prefix from that previous
154 -- line just as long as our indent. This gives us a bunch of
155 -- whitespace, with a few non-whitespace characters. We find out the
156 -- width of this prefix, and put whitespace just as wide as that
157 -- prefix before the current line, instead of the whitespace
158 -- characters that were there.
159 -- Doing this is slightly risky, since the prefix might contain
160 -- unfinished markup (e.g., \foo{bar without the closing }). We might
161 -- need to solve this later.
162 copyind = utf.sub(indentlines[prev], 1, #newind)
163 setwidth = "\\setwidthof{" .. copyind .. "}\\to\\pretlamalignwidth"
164 hskip = "\\hskip\\pretlamalignwidth"
165 return "{" .. setwidth .. hskip .. "}" .. rest
167 -- No previous line? Just return the unmodified line then
172 -- Mark the begin of a block of lambda formatted buffers or expressions. This
173 -- means that, until you call end_of_block again, the subscript bases are
174 -- shared. For example, if you have \lam{y1} some text \lam{yn} within a
175 -- single block, the yn will properly get subscripted. Be sure to call
176 -- end_of_block again!
178 -- Blocks can be partially nested, meaning that the block
179 -- won't be closed until end_of_block was called exactly as often as
180 -- begin_of_block. However, subscripts from the inner block can still
181 -- influence subscripts in the outer block.
182 function vis.begin_of_block()
183 vis.begin_of_display()
184 in_block = in_block + 1
187 -- Ends the current block
188 function vis.end_of_block()
189 in_block = in_block - 1
192 function vis.begin_of_display()
193 if in_block == 0 then
194 -- Initially allow subscripts using _ or just appending a number (later,
195 -- we will add extra patterns here.
196 submatches = {"^(%a*)_([%a%d,]+)$", "^(%a+)([%d,]+)$"}
197 -- This stores all the bases we've encountered so far (to prevent
198 -- duplicates). For each of them there will be a pattern in submatches
206 -- Make things work for inline typeing (e.g., \type{}) as well.
207 vis.begin_of_inline = vis.begin_of_display
208 vis.end_of_inline = vis.end_of_display
210 function vis.flush_line(str,nested)
211 local result, state = { }, 0
212 local finish, change = buffers.finish_state, buffers.change_state
214 -- Set the colorscheme, which is used by finish_state and change_state
215 buffers.currentcolors = colors
219 -- See if the next token is a word
220 word, str = take_word(str)
222 if keywords[res] then
223 -- Make all keywords bold
224 word = "{\\bold " .. word .. "}"
226 -- Process any subscripts in the word
227 word = do_subscripts(word)
230 -- The next token is not a word, it must be a symbol
231 symbol, str = take_symbol(str)
234 -- Append the resulting token
235 result[#result+1] = word or symbol
238 state = finish(state, result)
239 buffers.flush_result(result,nested)
242 -- vim: set sw=4 sts=4 expandtab ai: