Update the pret-trans to current context beta.

[matthijs/master-project/report.git] / pret-lam.lua

diff --git a/pret-lam.lua b/pret-lam.lua
index b882196ed522070743b40959e36a51940d8f5aee..eb7d3530395529a0b6ce1b934a4aa6ce4b38c467 100644 (file)
--- a/pret-lam.lua
+++ b/pret-lam.lua
@@ -6,41 +6,41 @@
 
 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
+vis = buffers.newvisualizer("lam")
 
-buffers.visualizers.lam.colors = {
+local colors = {
     "prettytwo",
     "prettyone",
     "prettythree",
     "prettyfour"
 }
 
-buffers.visualizers.lam.symbols = {
+-- Symbols that should have a different representation
+local symbols = {
     [' '] = {repr = '\\obs '},
     ['_'] = {repr = '\\_'},
     ['->'] = {repr = '\\rightarrow'},
     -- The default * sits very high above the baseline, \ast (u+2217) looks
     -- better.
     ['*'] = {repr = '\\ast'},
+    ['~'] = {repr = '\\sim'},
 }
 
-buffers.visualizers.lam.keywords = {
+
+-- Keywords that should be bold
+local keywords = {
     ['case'] = {},
     ['of'] = {},
     ['let'] = {},
     ['in'] = {},
 }
 
-
-function buffers.visualizers.lam.take_symbol(str)
-    -- 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.
-    for symbol,props in pairs(buffers.visualizers.lam.symbols) do
+-- 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.
+local function take_symbol(str)
+    for symbol,props in pairs(symbols) do
         -- Try to remove symbol from the start of str 
         symbol, newstr = utf.match(str, "^(" .. symbol .. ")(.*)")
         if symbol then
@@ -60,37 +60,78 @@ 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+)(.*)")
+local function take_word(str)
+        -- A word must always start with a-z (in particular, λ is not a valid
+        -- start of a word).
+        res, newstr = utf.match(str, "^([a-zA-Z][%a%d_]+)(.*)")
         return res, newstr or str
 end
 
-function buffers.visualizers.lam.flush_line(str,nested)
+-- 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.
+local function 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
+local function do_subscripts(word)
+    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,]+)$"
+        end
+    end
+    return word
+end
+
+function vis.begin_of_display()
+    -- Initially allow subscripts using _ or just appending a number (later,
+    -- we will add extra patterns here.
+    submatches = {"^(.*)_([%a%d,]+)$", "^(.*[^%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 vis.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
     -- Set the colorscheme, which is used by finish_state and change_state
-    buffers.currentcolors = buffers.visualizers.lam.colors
-
+    buffers.currentcolors = colors
     while str ~= "" do
         local found = false
-        local res
+        local word, symbol
         -- See if the next token is a word
-        res, str = take_word(str)
-        if res then
-            if buffers.visualizers.lam.keywords[res] then
-                -- Make all keywors bold
-                res = "{\\bold " .. res ..  "}"
+        word, str = take_word(str)
+        if word then
+            if keywords[res] then
+                -- Make all keywords bold
+                word = "{\\bold " .. word ..  "}"
+            else
+                -- Process any subscripts in the word
+                word = do_subscripts(word)
             end
-            -- All other words are unmodified
         else
             -- The next token is not a word, it must be a symbol
-            res, str = take_symbol(str)
+            symbol, str = take_symbol(str)
         end
 
         -- Append the resulting token
-        result[#result+1] = res
+        result[#result+1] = word or symbol
     end
 
     state = finish(state, result)