cal: implement content line parser

1 files changed, 158 insertions, 18 deletions

diff --git a/cal.lua b/cal.lua
index 6dd2c6b..709597a 100755
--- a/cal.lua
+++ b/cal.lua
@@ -11,26 +11,106 @@ local ioopen        = io.open
 local string        = require "string"
 local stringformat  = string.format
 
-local println       = function (...) print (stringformat (...)) end
+local table         = require "table"
+local tableconcat   = table.concat
+
+local verboselvl    = 3
+
+local mk_out = function (stream, threshold, newlinep)
+  local out = io.stdout
+  if stream == "err" or stream == "stderr" then out = io.stderr end
+  return function (...)
+    if verboselvl >= threshold then
+      local ok, msg = pcall (stringformat, ...)
+      if ok then
+        out:write (msg)
+        if newlinep == true then out:write "\n" end
+      ---else silently ignore
+      end
+    end
+  end
+end
+
+local println       = mk_out ("stdout", 0, true)
+local errorln       = mk_out ("stderr", 0, true)
+local noiseln       = mk_out ("stderr", 1, true)
+local debugln       = mk_out ("stderr", 2, true)
+
+local print_calendar
+local fmt_calendar_params
+do
+  fmt_calendar_params = function (params)
+    local acc = { }
+    local len = #params
+
+    for i = 1, len do
+      local params = params [i]
+      acc [i] = stringformat ("“%s” → “%s”", params.name, params.value)
+    end
+
+    return tableconcat (acc, ", ")
+  end
+end
 
 local parse_calendar do
   local lpeg            = require "lpeg"
   local lpegmatch       = lpeg.match
   local C               = lpeg.C
+  local Cf              = lpeg.Cf
+  local Cg              = lpeg.Cg
   local Cp              = lpeg.Cp
   local Cs              = lpeg.Cs
+  local Ct              = lpeg.Ct
   local P               = lpeg.P
+  local R               = lpeg.R
   local S               = lpeg.S
 
   local p_space         = P" "
   local p_cr            = P"\r"
   local p_lf            = P"\n"
 
-  local p_white_fold    = S" \t"
+  local p_wsp           = S" \t"
+  local p_white_fold    = p_wsp
   local p_white         = S" \n\r\t\v"
-  local p_eol           = p_cr * p_lf + p_lf
+  local p_eof           = P(-1)
+  local p_eol           = p_eof + p_cr * p_lf + p_lf
   local p_noeol         = P(1) - p_eol
 
+  local p_comma         = P","
+  local p_colon         = P":"
+  local p_semicolon     = P";"
+  local p_dash          = P"-"
+  local p_equals        = P"="
+  local p_dquote        = P"\""
+
+  local p_alpha         = R("az", "AZ")
+  local p_digit         = R"09"
+
+--[[--
+     NON-US-ASCII       = %x80-F8
+     QSAFE-CHAR         = WSP / %x21 / %x23-7E / NON-US-ASCII
+     SAFE-CHAR          = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E
+                        / NON-US-ASCII
+     VALUE-CHAR         = WSP / %x21-7E / NON-US-ASCII
+
+--]]--
+
+  local p_non_ascii     = R"\x7f\xff"
+  local p_value_char    = p_wsp
+                        + R"#~"       -- 0x23–0x7e
+                        + p_non_ascii
+  local p_qsafe_char    = p_wsp
+                        + P"!"        -- 0x21
+                        + R"#~"       -- 0x23–0x7e
+                        + p_non_ascii
+  local p_safe_char     = p_wsp --[[ printable range excluding {",:;} ]]
+                        + P"!"        -- 0x21
+                        + R"#+"       -- 0x23–0x2b
+                        + R"-9"       -- 0x2d–0x39
+                        + R"<~"       -- 0x3c–0x7e
+                        + p_non_ascii
+  ----- p_safe_char     = p_wsp + (R"!~" - S",:;")
+
   --[[--
 
     RFC2445: Long content lines SHOULD be split into a multiple line
@@ -44,42 +124,102 @@ local parse_calendar do
   local p_folded_line_1 = p_noeol^1 * (p_eol / "")
   local p_folded_line_c = p_white_fold/"" * p_folded_line_1
 
-  local p_content_line  = Cs(p_folded_line_1 * p_folded_line_c^0) * Cp()
+  local p_folded_line   = Cs(p_folded_line_1 * p_folded_line_c^0) * Cp()
 
   local p_skip_line     = p_noeol^0 * p_eol * Cp()
 
+  --[[--
+
+     contentline        = name *(";" param ) ":" value CRLF
+     name               = x-name / iana-token
+     iana-token         = 1*(ALPHA / DIGIT / "-")
+     x-name             = "X-" [vendorid "-"] 1*(ALPHA / DIGIT / "-")
+     vendorid           = 3*(ALPHA / DIGIT)     ;Vendor identification
+     param              = param-name "=" param-value
+                          *("," param-value)
+     param-name         = iana-token / x-token
+     param-value        = paramtext / quoted-string
+     paramtext          = *SAFE-CHAR
+     value              = *VALUE-CHAR
+     quoted-string      = DQUOTE *QSAFE-CHAR DQUOTE
+
+  --]]--
+
+  local add_param = function (t, k, v)
+    debugln ("»»»» add_param ({%s}, %s, %s)", t, tostring (k), tostring (v))
+
+    t [#t + 1] = { name = k, value = v }
+
+    return t
+  end
+
+  local p_quoted_string = p_dquote * p_qsafe_char^0 * p_dquote
+  local p_ianatok       = (p_alpha + p_digit + p_dash)^1
+  local p_xtok          = nil --[[ XXX rule missing from RFC ]]
+  local p_param_name    = p_ianatok -- + p_xtok
+  local p_param_text    = p_safe_char^0
+  local p_value         = p_value_char^0
+  local p_param_value   = p_param_text + p_quoted_string
+  local p_param         = Cg (  C(p_param_name)
+                              * p_equals
+                              * Ct(C(p_param_value) * (p_comma * C(p_param_value))^0))
+  local p_params        = Cf (Ct"" * (p_semicolon * p_param)^0, add_param)
+  local p_vendorid      = (p_alpha + p_digit)^3
+  local p_xname         = P"X" * p_dash * (p_vendorid * p_dash)^-1
+                        * (p_ianatok)
+  local p_name          = p_xname + p_ianatok
+  local p_content_line  = C(p_name)
+                        * p_params^-1
+                        * p_colon * C(p_value) * Cp()
+
   local parse_content_line = function (raw, pos0)
-    local res, pos1 = lpegmatch (p_content_line, raw, pos0)
+    local tmp, pos1 = lpegmatch (p_folded_line, raw, pos0)
+    if tmp == nil then return false end
 
-    return res, pos1
+    local name, params, value, epos
+    name, params, value, epos = lpegmatch (p_content_line, tmp)
+
+    if name == nil or value == nil then return false end
+
+    if epos ~= #tmp + 1 then
+      noiseln ("parsing unfolded line stopped %d characters short \z
+                of EOL [%d]“%s”", epos - #tmp - 1, #tmp, tmp)
+    end
+
+    return true, pos1, name, params, value
   end
 
   local skip_line = function (raw, pos0)
     return lpegmatch (p_skip_line, raw, pos0)
   end
 
-  local errline = function (pos)
-  end
+  parse_calendar = function (raw, pos0, acc, consumed, nline, nskipped)
+    if pos0 == nil then return parse_calendar (raw, 1, { }, 0, 1, 0) end
 
-  parse_calendar = function (raw, pos0, consumed, nline, nskipped)
-    if pos0 == nil then return parse_calendar (raw, 1, 0, 1) end
+    local ok, pos1, name, params, value = parse_content_line (raw, pos0)
 
-    local cline, pos1 = parse_content_line (raw, pos0)
-    if cline == nil then
+    if ok == false then
       pos1 = skip_line (raw, pos0)
-      println ("[%d–%d] %d bad content line; skipping", pos0, pos1, nline)
+      if pos0 == pos1 then
+        noiseln ("»»» [%d] reached EOF, terminating after %d bytes, \z
+                  %d calendar lines",
+                 pos0, consumed, nline)
+        return acc
+      end
+      errorln ("[%d–%d] %d bad content line; skipping", pos0, pos1, nline)
       nskipped = nskipped + 1
     else
-      println ("[%d–%d] %d [%s]", pos0, pos1, nline, cline)
+      noiseln ("»»» [%d–%d] “%s” [%s] “%s”",
+               pos0, pos1, name, fmt_calendar_params (params), value)
+      acc [#acc + 1] = { pos = { pos0, pos1 }
+                       , name = name, params = params, value = value }
     end
-    return parse_calendar (raw, pos1, consumed + pos1 - pos0, nline + 1,
+
+    return parse_calendar (raw, pos1, acc, consumed + (pos1 - pos0), nline + 1,
                            nskipped)
   end
 end
 
-local print_calendar do
-end
-
 local loaddata = function (fname)
   local fh = ioopen (fname, "r")