Move code from __init__ to main_parser.py

Actually, parse_io is quite close to a yet another parser which just
calls other parsers. So let's implement parse_io as as MainParser, which
is called a single time from gmshparser.parse.

docs/api.rst

@@ -56,6 +56,9 @@ function `parse`, which is responsible of parsing a section.
 .. autoclass:: gmshparser.abstract_parser.AbstractParser
    :members:
 
+.. autoclass:: gmshparser.main_parser.MainParser
+   :members:
+
 .. autoclass:: gmshparser.mesh_format_parser.MeshFormatParser
    :members:
 

gmshparser/__init__.py

@@ -1,38 +1,12 @@
-from typing import TextIO
 from .mesh import Mesh
-from .mesh_format_parser import MeshFormatParser
-from .nodes_parser import NodesParser
-from .elements_parser import ElementsParser
-
-
-DEFAULT_PARSERS = {
-    "$MeshFormat": MeshFormatParser,
-    "$Nodes": NodesParser,
-    "$Elements": ElementsParser,
-}
-
-
-def parse_io(io: TextIO, mesh=Mesh(), parsers=DEFAULT_PARSERS) -> Mesh:
-    """Parse input stream using `parsers` to `mesh` object. """
-    for line in io:
-        line = line.strip()
-        if not line.startswith("$"):
-            continue
-        if line.startswith("$End"):
-            continue
-        if line not in parsers:
-            continue
-        try:
-            parsers[line]().parse(mesh, io)
-        except Exception:
-            print("Unable to parse section %s from mesh!" % line)
-            raise
-    return mesh
+from .main_parser import MainParser
 
 
 def parse(filename: str) -> Mesh:
     """Parse Gmsh .msh file and return `Mesh` object."""
-    with open(filename, "r") as fid:
-        mesh = parse_io(fid)
-        mesh.set_name(filename)
-        return mesh
+    mesh = Mesh()
+    mesh.set_name(filename)
+    parser = MainParser()
+    with open(filename, "r") as io:
+        parser.parse(mesh, io)
+    return mesh

gmshparser/main_parser.py

@@ -0,0 +1,32 @@
+from typing import TextIO
+from .mesh import Mesh
+from .mesh_format_parser import MeshFormatParser
+from .nodes_parser import NodesParser
+from .elements_parser import ElementsParser
+from .abstract_parser import AbstractParser
+
+
+DEFAULT_PARSERS = [
+    MeshFormatParser,
+    NodesParser,
+    ElementsParser,
+]
+
+
+class MainParser(AbstractParser):
+
+    """ The main parser class, using other parsers. """
+
+    def __init__(self, parsers=DEFAULT_PARSERS):
+        self.parsers = parsers
+
+    def parse(self, mesh: Mesh, io: TextIO) -> None:
+        for line in io:
+            line = line.strip()
+            for parser in self.parsers:
+                if parser.get_section_name() == line:
+                    try:
+                        parser.parse(mesh, io)
+                    except Exception:
+                        print("Unable to parse section %s from mesh!" % line)
+                        raise

tests/test_abstract_parser.py

@@ -3,6 +3,8 @@
 
 
 def test_abstract_parser():
+    with pytest.raises(NotImplementedError):
+        AbstractParser.get_section_name()
     p = AbstractParser()
     with pytest.raises(NotImplementedError):
         p.parse(1, 2)

tests/test_main_parser.py

@@ -0,0 +1,39 @@
+from gmshparser import MainParser
+from gmshparser.mesh import Mesh
+from io import StringIO
+from pytest import raises
+
+
+__content__ = StringIO("""
+$MeshFormat
+4.1 0 8
+$EndMeshFormat
+$Unknown
+my custom data
+$EndUnknown
+""")
+
+
+__bad_content__ = StringIO("""
+$MeshFormat
+4.1 0 8          MSH4.1, ASCII
+$EndMeshFormat
+$Nodes
+1 6 1 6          1 entity bloc, 6 nodes total, min/max node tags: 1 and 6
+2 1 0 6          2D entity (surface) 1, no parametric coordinates, 6 nodes
+$EndNodes
+""".strip())
+
+
+def test_mainparser():
+    parser = MainParser()
+    mesh = Mesh()
+    parser.parse(mesh, __content__)
+    assert mesh.get_version() == 4.1
+
+
+def test_parse_io_bad_content():
+    parser = MainParser()
+    mesh = Mesh()
+    with raises(Exception):
+        parser.parse(mesh, __bad_content__)