Support line numbers for pl.lexer with string arg

lua/pl/lexer.lua

@@ -159,7 +159,7 @@ function lexer.scan(s,matches,filter,options)
         matches = plain_matches
     end
     local function lex()
-        local line_nr = 0
+        local line_nr = file and 0 or 1
         local next_line = file and file:read()
         local sz = file and 0 or #s
         local idx = 1
@@ -193,6 +193,11 @@ function lexer.scan(s,matches,filter,options)
                         lexer.finished = idx > sz
                         res = fun(tok, options, findres)
                     end
+                    if not file and tok:find("\n") then
+                        -- Update line number.
+                        local _, newlines = tok:gsub("\n", {})
+                        line_nr = line_nr + newlines
+                    end
                     if res then
                         local tp = type(res)
                         -- insert a token list
@@ -258,9 +263,10 @@ function lexer.getline (tok)
 end
 
 --- get current line number.
--- Only available if the input source is a file-like object.
 -- @param tok a token stream
--- @return the line number and current column
+-- @return the line number.
+-- if the input source is a file-like object,
+-- also return the column.
 function lexer.lineno (tok)
     return tok(0)
 end

tests/test-lexer.lua

@@ -120,3 +120,13 @@ test_scan([['' "" " \\" '\'' "'"]], nil, nil, {
     {'char', "\\'"},
     {'string', "'"}
 }, 'cpp')
+
+local iter = lexer.lua([[
+foo
+bar
+]])
+
+iter()
+asserteq(lexer.lineno(iter), 1)
+iter()
+asserteq(lexer.lineno(iter), 2)