1 files changed, 61 insertions, 0 deletions
diff --git a/bsie/matcher/matcher.py b/bsie/matcher/matcher.py
new file mode 100644
index 0000000..a89626f
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+++ b/bsie/matcher/matcher.py
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+
+# standard imports
+import abc
+import typing
+
+# bsie imports
+from bsie.utils import bsfs
+
+# inner-module imports
+from . import nodes
+
+# exports
+__all__: typing.Sequence[str] = (
+    'Matcher',
+    )
+
+
+## code ##
+
+class Matcher():
+    """Determine node uri's from node hints."""
+    def __call__(
+            self,
+            iterable: typing.Iterable[typing.Tuple[nodes.Node, bsfs.URI, typing.Any]],
+            ):
+        """Apply the matcher on a triple iterator."""
+        return MatcherIterator(self, iterable)
+
+    @abc.abstractmethod
+    def match_node(self, node: nodes.Node) -> nodes.Node:
+        """Apply the matcher on a node."""
+
+
+class MatcherIterator():
+    """Iterates over triples, determines uris according to a *matcher* as it goes."""
+
+    # source triple iterator.
+    _iterable: typing.Iterable[typing.Tuple[nodes.Node, bsfs.URI, typing.Any]]
+
+    # node matcher
+    _matcher: Matcher
+
+    def __init__(
+            self,
+            matcher: Matcher,
+            iterable: typing.Iterable[typing.Tuple[nodes.Node, bsfs.URI, typing.Any]],
+            ):
+        self._iterable = iterable
+        self._matcher = matcher
+
+    def __iter__(self):
+        for node, pred, value in self._iterable:
+            # handle subject
+            self._matcher.match_node(node)
+            # handle value
+            if isinstance(value, nodes.Node):
+                self._matcher.match_node(value)
+            # yield triple
+            yield node, pred, value
+
+## EOF ##