efficient build

- postpone building until really needed
- rebuild only if artifacts change
- no build on source update
- prune takes current resolver state instead of global var

lektor_groupby/model.py

@@ -0,0 +1,66 @@
+from lektor.db import Database, Record  # typing
+from lektor.types.flow import Flow, FlowType
+from lektor.utils import bool_from_string
+from typing import Set, Dict, Tuple, Any, NamedTuple, Optional, Iterator
+
+
+class FieldKeyPath(NamedTuple):
+    fieldKey: str
+    flowIndex: Optional[int] = None
+    flowKey: Optional[str] = None
+
+
+class ModelReader:
+    '''
+    Find models and flow-models which contain attribute.
+    Flows are either returned directly (flatten=False) or
+    expanded so that each flow-block is yielded (flatten=True)
+    '''
+
+    def __init__(self, db: Database, attr: str, flatten: bool = False) -> None:
+        self.flatten = flatten
+        self._flows = {}  # type: Dict[str, Set[str]]
+        self._models = {}  # type: Dict[str, Dict[str, str]]
+        # find flow blocks containing attribute
+        for key, flow in db.flowblocks.items():
+            tmp1 = set(f.name for f in flow.fields
+                       if bool_from_string(f.options.get(attr, False)))
+            if tmp1:
+                self._flows[key] = tmp1
+        # find models and flow-blocks containing attribute
+        for key, model in db.datamodels.items():
+            tmp2 = {}  # Dict[str, str]
+            for field in model.fields:
+                if bool_from_string(field.options.get(attr, False)):
+                    tmp2[field.name] = '*'  # include all children
+                elif isinstance(field.type, FlowType) and self._flows:
+                    # only processed if at least one flow has attr
+                    fbs = field.type.flow_blocks
+                    # if fbs == None, all flow-blocks are allowed
+                    if fbs is None or any(x in self._flows for x in fbs):
+                        tmp2[field.name] = '?'  # only some flow blocks
+            if tmp2:
+                self._models[key] = tmp2
+
+    def read(self, record: Record) -> Iterator[Tuple[FieldKeyPath, Any]]:
+        ''' Enumerate all fields of a Record with attrib = True. '''
+        assert isinstance(record, Record)
+        for r_key, subs in self._models.get(record.datamodel.id, {}).items():
+            field = record[r_key]
+            if not field:
+                continue
+            if subs == '*':  # either normal field or flow type (all blocks)
+                if self.flatten and isinstance(field, Flow):
+                    for i, flow in enumerate(field.blocks):
+                        flowtype = flow['_flowblock']
+                        for f_key, block in flow._data.items():
+                            if f_key.startswith('_'):  # e.g., _flowblock
+                                continue
+                            yield FieldKeyPath(r_key, i, f_key), block
+                else:
+                    yield FieldKeyPath(r_key), field
+            else:  # always flow type (only some blocks)
+                for i, flow in enumerate(field.blocks):
+                    flowtype = flow['_flowblock']
+                    for f_key in self._flows.get(flowtype, []):
+                        yield FieldKeyPath(r_key, i, f_key), flow[f_key]