X-Git-Url: https://git.stderr.nl/gitweb?p=matthijs%2Fmaster-project%2Freport.git;a=blobdiff_plain;f=pret-lam.lua;h=eb7d3530395529a0b6ce1b934a4aa6ce4b38c467;hp=15fcf9a3ac1fdc6343dd3e90077047d713921983;hb=3ff8ced65f6af69db754b35b263c7d6d9f19e61f;hpb=95b1a682e51c47d635d5bafe75bd7096e8d4ec18

diff --git a/pret-lam.lua b/pret-lam.lua
index 15fcf9a..eb7d353 100644
--- a/pret-lam.lua
+++ b/pret-lam.lua
@@ -6,55 +6,134 @@
 
 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.tokens = {
+-- Symbols that should have a different representation
+local symbols = {
     [' '] = {repr = '\\obs '},
+    ['_'] = {repr = '\\_'},
     ['->'] = {repr = '\\rightarrow'},
-    ['case'] = {style = 'bold'},
-    ['of'] = {style = 'bold'},
-    ['let'] = {style = 'bold'},
+    -- The default * sits very high above the baseline, \ast (u+2217) looks
+    -- better.
+    ['*'] = {repr = '\\ast'},
+    ['~'] = {repr = '\\sim'},
 }
 
-function buffers.visualizers.lam.flush_line(str,nested)
+
+-- Keywords that should be bold
+local keywords = {
+    ['case'] = {},
+    ['of'] = {},
+    ['let'] = {},
+    ['in'] = {},
+}
+
+-- 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
+            -- Return this tokens repr, or just the token if it has no
+            -- repr.
+            res = props.repr or symbol
+            -- Enclose the token in {\style .. }
+            if props.style then
+                res = "{\\" .. props.style ..  " " .. res ..  "}"
+            end
+            return res, newstr
+        end
+    end
+    -- No symbol found, just return the first character
+    return utf.match(str, "^(.)(.*)")
+end
+
+-- Take a single word from str, if posible. Returns the rest of the string and
+-- the word taken.
+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
+
+-- 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
     -- Set the colorscheme, which is used by finish_state and change_state
-    buffers.currentcolors = buffers.visualizers.lam.colors
-
+    buffers.currentcolors = colors
     while str ~= "" do
-        found = false
-        for tok,props in pairs(buffers.visualizers.lam.tokens) do
-            -- Try to remove tok from the start of str 
-            str, count = utf.gsub(str, "^" .. tok, "")
-            if count ~= 0 then
-                -- Replace the token with the repr, or just itself
-                result[#result+1] = props.repr or tok
-                -- Enclose the token in {\style .. }
-                if props.style then
-                    result[#result] = "{\\" .. props.style ..
-                                        " " .. result[#result] ..
-                                        "}"
-                end
-                -- We found a token, now start over
-                found = true
-                break
+        local found = false
+        local word, symbol
+        -- See if the next token is a word
+        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
+        else
+            -- The next token is not a word, it must be a symbol
+            symbol, str = take_symbol(str)
         end
-        if not found then
-            result[#result+1] = utf.sub(str, 1, 1)
-            str = utf.sub(str, 2)
-        end
+
+        -- Append the resulting token
+        result[#result+1] = word or symbol
     end
+
     state = finish(state, result)
     buffers.flush_result(result,nested)
 end