From 2b596488ddf1e401f7bb51411775bbced4f07185 Mon Sep 17 00:00:00 2001
From: Daniel Silverstone <dsilvers@digital-scurf.org>
Date: Sun, 13 May 2012 23:17:01 +0100
Subject: Allow empty quotes to force an empty word to get into the lexer
 output

---
 lib/lace/lex.lua       |  8 ++++++--
 test/test-lace.lex.lua | 12 ++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/lib/lace/lex.lua b/lib/lace/lex.lua
index f8e5160..ba9dabe 100644
--- a/lib/lace/lex.lua
+++ b/lib/lace/lex.lua
@@ -15,6 +15,7 @@ local function lex_one_line(line)
    local c
    local escaping = false
    local quoting = false
+   local force_empty = false
    local spos, cpos = 1, 0
    while #line > 0 do
       c, line = line:match("^(.)(.*)$")
@@ -36,9 +37,11 @@ local function lex_one_line(line)
 	 if c == "'" and quoting == false then
 	    -- Start single quotes
 	    quoting = c
+	    force_empty = true
 	 elseif c == '"' and quoting == false then
 	    -- Start double quotes
 	    quoting = c
+	    force_empty = true
 	 elseif c == "'" and quoting == c then
 	    -- End single quotes
 	    quoting = false
@@ -53,9 +56,10 @@ local function lex_one_line(line)
 	    acc = acc .. c
 	 elseif c == " " or c == "\t" then
 	    -- A space (or tab) and not quoting, so clear the accumulator
-	    if acc ~= "" then
+	    if acc ~= "" or force_empty then
 	       r[#r+1] = { spos = spos, epos = cpos - 1, str = acc }
 	       spos = cpos + 1
+	       force_empty = false
 	    elseif cpos == spos then
 	       -- Increment the start position since we've not found a word yet
 	       spos = spos + 1
@@ -66,7 +70,7 @@ local function lex_one_line(line)
 	 end
       end
    end
-   if acc ~= "" then
+   if acc ~= "" or force_empty then
       r[#r+1] = { spos = spos, epos = cpos, str = acc }
    end
 
diff --git a/test/test-lace.lex.lua b/test/test-lace.lex.lua
index 5d9d552..41f1685 100644
--- a/test/test-lace.lex.lua
+++ b/test/test-lace.lex.lua
@@ -248,6 +248,18 @@ function suite.escape_inside_unclosed_unused()
    assert(content.lines[1].warnings[2]:find("escape"), "The warning should be about the escape")
 end
 
+function suite.empty_string_words_work()
+   local content = assert(lex.string("allow ''", "SRC"))
+   assert(content.source == "SRC", "Source name not propagated")
+   assert(type(content.lines) == "table", "Lines is not a table")
+   assert(#content.lines == 1, "There should have been one line")
+   assert(#content.lines[1].content == 2, "The line should have 2 words")
+   assert(content.lines[1].content[1].spos == 1, "The first word starts at the first character")
+   assert(content.lines[1].content[1].str == "allow", "The word is \"allow\"")
+   assert(content.lines[1].content[2].str == "", "The second word is empty")
+   assert(content.lines[1].content[2].spos == 7, "The empty word starts at the seventh character")
+end
+
 local count_ok = 0
 for _, testname in ipairs(testnames) do
    print("Run: " .. testname)
-- 
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