Optimization: support loading only one sheet from many in order to save memory usage

pyexcel_xls/__init__.py

@@ -103,21 +103,38 @@ class XLBook(BookReader):
 
     It reads xls, xlsm, xlsx work book
     """
+    def __init__(self, filename, file_content=None, sheetname=None, **keywords):
+        BookReader.__init__(self, filename, file_content=file_content, sheetname=sheetname, **keywords)
+        self.native_book.release_resources()
+        
     def sheetIterator(self):
         """Return iterable sheet array"""
-        return self.native_book.sheets()
+        
+        if self.sheet_name is not None:
+            return [self.native_book.sheet_by_name(self.sheet_name)]
+        elif self.sheet_index is not None:
+            return [self.native_book.sheet_by_index(self.sheet_index)]
+        else:
+            return self.native_book.sheets()
 
     def getSheet(self, native_sheet):
         """Create a xls sheet"""
         return XLSheet(native_sheet)
 
-    def load_from_memory(self, file_content):
+    def load_from_memory(self, file_content, **keywords):
         """Provide the way to load xls from memory"""
-        return xlrd.open_workbook(None, file_contents=file_content)
+        on_demand = False
+        if self.sheet_name is not None or self.sheet_index is not None:
+            on_demand = True
+        return xlrd.open_workbook(None, file_contents=file_content,
+                                      on_demand=on_demand)
 
-    def load_from_file(self, filename):
+    def load_from_file(self, filename, **keywords):
         """Provide the way to load xls from a file"""
-        return xlrd.open_workbook(filename)
+        on_demand = False
+        if self.sheet_name is not None or self.sheet_index is not None:
+            on_demand = True
+        return xlrd.open_workbook(filename, on_demand=on_demand)
 
 
 class XLSheetWriter(SheetWriter):
@@ -198,4 +215,4 @@ except:
     # to allow this module to function independently
     pass
 
-__VERSION__ = "0.0.5"
+__VERSION__ = "0.0.6"

setup.py

@@ -12,7 +12,7 @@ with open("README.rst", 'r') as readme:
 dependencies = [
     'xlrd',
     'xlwt-future',
-    'pyexcel-io>=0.0.2'
+    'pyexcel-io>=0.0.3'
 ]
 if sys.version_info[0] == 2 and sys.version_info[1] < 7:
     dependencies.append('ordereddict')
@@ -20,7 +20,7 @@ if sys.version_info[0] == 2 and sys.version_info[1] < 7:
 setup(
     name='pyexcel-xls',
     author="C. W.",
-    version='0.0.5',
+    version='0.0.6',
     author_email="wangc_2011@hotmail.com",
     url="https://github.com/chfw/pyexcel-xls",
     description='A wrapper library to read, manipulate and write data in xls format. It reads xlsx and xlsm format',

tests/test_mutliple_sheets.py

@@ -19,21 +19,6 @@ class TestXlsNxlsMultipleSheets(PyexcelMultipleSheetBase):
         self._clean_up()
 
 
-#class TestXlsNXlsxMultipleSheets(PyexcelMultipleSheetBase):
-#    def setUp(self):
-#        self.testfile = "multiple1.xls"
-#        self.testfile2 = "multiple1.xlsx"
-#        self.content = {
-#            "Sheet1": [[1, 1, 1, 1], [2, 2, 2, 2], [3, 3, 3, 3]],
-#            "Sheet2": [[4, 4, 4, 4], [5, 5, 5, 5], [6, 6, 6, 6]],
-#            "Sheet3": [[u'X', u'Y', u'Z'], [1, 4, 7], [2, 5, 8], [3, 6, 9]]
-#        }
-#        self._write_test_file(self.testfile)
-#
-#    def tearDown(self):
-#        self._clean_up()
-
-
 class TestAddBooks:
     def _write_test_file(self, file):
         """
@@ -60,6 +45,16 @@ class TestAddBooks:
         self._write_test_file(self.testfile)
         self._write_test_file(self.testfile2)
 
+    def test_load_a_single_sheet(self):
+        b1 = pyexcel.load_book(self.testfile, sheet_name="Sheet1")
+        assert len(b1.sheet_names()) == 1
+        assert b1['Sheet1'].to_array() == self.content['Sheet1']
+
+    def test_load_a_single_sheet2(self):
+        b1 = pyexcel.load_book(self.testfile, sheet_index=0)
+        assert len(b1.sheet_names()) == 1
+        assert b1['Sheet1'].to_array() == self.content['Sheet1']
+
     def test_delete_sheets(self):
         b1 = pyexcel.load_book(self.testfile)
         assert len(b1.sheet_names()) == 3