Add trim(), split_unit() and split_string() Lua helper functions

src/init.lua

@@ -14,14 +14,20 @@ local _define_table_impl = function(_type, _name, _columns, _options)
 end
 
 function osm2pgsql.has_prefix(str, prefix)
+    if str == nil then
+        return nil
+    end
     return str:sub(1, prefix:len()) == prefix
 end
 
 function osm2pgsql.has_suffix(str, suffix)
+    if str == nil then
+        return nil
+    end
     if suffix == '' then
         return true
     end
-    return str:sub(- suffix:len()) == suffix
+    return str:sub(- #suffix) == suffix
 end
 
 function osm2pgsql.define_node_table(_name, _columns, _options)
@@ -51,6 +57,9 @@ function osm2pgsql.way_member_ids(relation)
 end
 
 function osm2pgsql.clamp(value, low, high)
+    if value == nil then
+        return nil
+    end
     return math.min(math.max(value, low), high)
 end
 
@@ -116,6 +125,47 @@ function osm2pgsql.make_clean_tags_func(keys)
     end
 end
 
+-- from http://lua-users.org/wiki/StringTrim
+function osm2pgsql.trim(str)
+    if str == nil then
+        return nil
+    end
+    local from = str:match("^%s*()")
+    return from > #str and "" or str:match(".*%S", from)
+end
+
+function osm2pgsql.split_unit(str, default_unit)
+    if str == nil then
+        return nil
+    end
+
+    local val, unit = string.match(str, "^(-?[0-9.]+) ?(%a*)$")
+    if val == nil then
+        return nil
+    end
+
+    if unit == '' then
+        unit = default_unit
+    end
+
+    val = tonumber(val)
+
+    return val, unit
+end
+
+function osm2pgsql.split_string(str, separator)
+    local result = {}
+
+    if str ~= nil then
+        local pattern = '([^' .. (separator or ';') .. ']+)'
+        for w in string.gmatch(str, pattern) do
+            result[#result + 1] = osm2pgsql.trim(w)
+        end
+    end
+
+    return result
+end
+
 -- This will be the metatable for the OSM objects given to the process callback
 -- functions.
 local inner_metatable = {

tests/lua/tests.lua

@@ -20,6 +20,7 @@ assert(o.has_prefix('addr:city', ''))
 assert(not o.has_prefix('name', 'addr:'))
 assert(o.has_prefix('a', 'a'))
 assert(not o.has_prefix('a', 'ab'))
+assert(o.has_prefix(nil, 'a') == nil)
 
 -- has_suffix()
 
@@ -29,6 +30,7 @@ assert(o.has_suffix('tiger:source', ''))
 assert(not o.has_suffix('name', ':source'))
 assert(o.has_suffix('a', 'a'))
 assert(not o.has_suffix('a', 'ba'))
+assert(o.has_suffix(nil, 'a') == nil)
 
 -- ---------------------------------------------------------------------------
 
@@ -39,6 +41,7 @@ do
     assert(o.clamp(3, -1, 1) == 1)
     assert(o.clamp(-3, -1, 1) == -1)
     assert(o.clamp(2.718, 0, 3.141) == 2.718)
+    assert(o.clamp(nil, -1, 1) == nil)
 end
 
 -- make_check_values_func without default
@@ -98,6 +101,101 @@ do
     assert(num == 3)
 end
 
+-- trim
+assert(osm2pgsql.trim('') == '')
+assert(osm2pgsql.trim(' ') == '')
+assert(osm2pgsql.trim('  ') == '')
+assert(osm2pgsql.trim('a') == 'a')
+assert(osm2pgsql.trim(' a') == 'a')
+assert(osm2pgsql.trim('a ') == 'a')
+assert(osm2pgsql.trim(' a ') == 'a')
+assert(osm2pgsql.trim('  a  ') == 'a')
+assert(osm2pgsql.trim('  ab cd  ') == 'ab cd')
+assert(osm2pgsql.trim(' \t\r\n\f\va\000b \r\t\n\f\v') == 'a\000b')
+assert(osm2pgsql.trim(nil) == nil)
+
+-- split_unit
+
+v, u = o.split_unit('20m', '')
+assert(v == 20 and u == 'm')
+
+v, u = o.split_unit('20 m')
+assert(v == 20 and u == 'm')
+
+v, u = o.split_unit('20ft', '')
+assert(v == 20 and u == 'ft')
+
+v, u = o.split_unit('23.4 ft', '')
+assert(v == 23.4 and u == 'ft')
+
+v, u = o.split_unit('20 ft', 'm')
+assert(v == 20 and u == 'ft')
+
+v, u = o.split_unit('20km', 'm')
+assert(v == 20 and u == 'km')
+
+v, u = o.split_unit('20')
+assert(v == 20 and u == nil)
+
+v, u = o.split_unit('20', 'm')
+assert(v == 20 and u == 'm')
+
+v, u = o.split_unit('0', 'm')
+assert(v == 0 and u == 'm')
+
+v, u = o.split_unit('-20000', 'leagues')
+assert(v == -20000 and u == 'leagues')
+
+v, u = o.split_unit('20xx20', '')
+assert(v == nil)
+
+v, u = o.split_unit('20-20', '')
+assert(v == nil)
+
+v, u = o.split_unit('20xx20', 'foo')
+assert(v == nil)
+
+v, u = o.split_unit('abc', 'def')
+assert(v == nil)
+
+v, u = o.split_unit(nil)
+assert(v == nil and u == nil)
+
+v, u = o.split_unit(nil, 'foo')
+assert(v == nil and u == nil)
+
+-- split_string
+
+r = o.split_string('ab c;d;e f;ghi')
+assert(#r == 4)
+assert(r[1] == 'ab c')
+assert(r[2] == 'd')
+assert(r[3] == 'e f')
+assert(r[4] == 'ghi')
+
+r = o.split_string('ab c;d  ;  e f; ghi')
+assert(#r == 4)
+assert(r[1] == 'ab c')
+assert(r[2] == 'd')
+assert(r[3] == 'e f')
+assert(r[4] == 'ghi')
+
+r = o.split_string('ab c ')
+assert(#r == 1)
+assert(r[1] == 'ab c')
+
+r = o.split_string('')
+assert(#r == 0)
+
+r = o.split_string('ab c;d  ,  e f, ghi', ',')
+assert(#r == 3)
+assert(r[1] == 'ab c;d')
+assert(r[2] == 'e f')
+assert(r[3] == 'ghi')
+
+r = o.split_string(nil)
+assert(#r == 0)
+
 -- ---------------------------------------------------------------------------
 
 print("All tests successful")