Implement count function

implementations/python/preserves/path.prb

@@ -1,5 +1,5 @@
-´³schema·³version‘³definitions·³Axis´³orµµ±values´³rec´³lit³values„´³tupleµ„„„„µ±descendants´³rec´³lit³descendants„´³tupleµ„„„„µ±at´³rec´³lit³at„´³tupleµ´³named³key³any„„„„„µ±label´³rec´³lit³label„´³tupleµ„„„„µ±keys´³rec´³lit³keys„´³tupleµ„„„„µ±length´³rec´³lit³length„´³tupleµ„„„„µ±annotations´³rec´³lit³annotations„´³tupleµ„„„„µ±embedded´³rec´³lit³embedded„´³tupleµ„„„„µ±parse´³rec´³lit³parse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„µ±unparse´³rec´³lit³unparse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„„„³Step´³orµµ±Axis´³refµ„³Axis„„µ±Filter´³refµ„³Filter„„„„³Filter´³orµµ±nop´³rec´³lit³nop„´³tupleµ„„„„µ±compare´³rec´³lit³compare„´³tupleµ´³named³op´³refµ„³
-Comparison„„´³named³literal³any„„„„„µ±regex´³rec´³lit³regex„´³tupleµ´³named³regex´³atom³String„„„„„„µ±test´³rec´³lit³test„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±real´³rec´³lit³real„´³tupleµ„„„„µ±int´³rec´³lit³int„´³tupleµ„„„„µ±kind´³rec´³lit³kind„´³tupleµ´³named³kind´³refµ„³	ValueKind„„„„„„„„³Selector´³seqof´³refµ„³Step„„³	Predicate´³orµµ±Selector´³refµ„³Selector„„µ±not´³rec´³lit³not„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±or´³rec´³lit³or„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„µ±and´³rec´³lit³and„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„„„³	ValueKind´³orµµ±Boolean´³lit³Boolean„„µ±Float´³lit³Float„„µ±Double´³lit³Double„„µ±
SignedInteger´³lit³
SignedInteger„„µ±String´³lit³String„„µ±
+´³schema·³version‘³definitions·³Axis´³orµµ±values´³rec´³lit³values„´³tupleµ„„„„µ±descendants´³rec´³lit³descendants„´³tupleµ„„„„µ±at´³rec´³lit³at„´³tupleµ´³named³key³any„„„„„µ±label´³rec´³lit³label„´³tupleµ„„„„µ±keys´³rec´³lit³keys„´³tupleµ„„„„µ±length´³rec´³lit³length„´³tupleµ„„„„µ±annotations´³rec´³lit³annotations„´³tupleµ„„„„µ±embedded´³rec´³lit³embedded„´³tupleµ„„„„µ±parse´³rec´³lit³parse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„µ±unparse´³rec´³lit³unparse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„„„³Step´³orµµ±Axis´³refµ„³Axis„„µ±Filter´³refµ„³Filter„„µ±Function´³refµ„³Function„„„„³Filter´³orµµ±nop´³rec´³lit³nop„´³tupleµ„„„„µ±compare´³rec´³lit³compare„´³tupleµ´³named³op´³refµ„³
+Comparison„„´³named³literal³any„„„„„µ±regex´³rec´³lit³regex„´³tupleµ´³named³regex´³atom³String„„„„„„µ±test´³rec´³lit³test„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±real´³rec´³lit³real„´³tupleµ„„„„µ±int´³rec´³lit³int„´³tupleµ„„„„µ±kind´³rec´³lit³kind„´³tupleµ´³named³kind´³refµ„³	ValueKind„„„„„„„„³Function´³rec´³lit³count„´³tupleµ´³named³selector´³refµ„³Selector„„„„„³Selector´³seqof´³refµ„³Step„„³	Predicate´³orµµ±Selector´³refµ„³Selector„„µ±not´³rec´³lit³not„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±or´³rec´³lit³or„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„µ±and´³rec´³lit³and„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„„„³	ValueKind´³orµµ±Boolean´³lit³Boolean„„µ±Float´³lit³Float„„µ±Double´³lit³Double„„µ±
SignedInteger´³lit³
SignedInteger„„µ±String´³lit³String„„µ±
 ByteString´³lit³
 ByteString„„µ±Symbol´³lit³Symbol„„µ±Record´³lit³Record„„µ±Sequence´³lit³Sequence„„µ±Set´³lit³Set„„µ±
 Dictionary´³lit³

implementations/python/preserves/path.py

@@ -57,12 +57,17 @@ FILTER_SET = Symbol('set')
 FILTER_DICT = Symbol('dict')
 FILTER_EMBEDDED = Symbol('embedded')
 
+FUNCTION_COUNT = Symbol('count')
+
 TRANSFORM_REAL = Symbol('~real')
 TRANSFORM_INT = Symbol('~int')
 
 def parse_step(tokens):
     t = next(tokens)
-    if isinstance(t, tuple): return syntax.Step.Filter(syntax.Filter.test(parse_predicate(iter(t))))
+    if isinstance(t, tuple): return syntax.Step.Filter(syntax.Filter.test(parse_predicate(t)))
+    if isinstance(t, Record):
+        if t.key == FUNCTION_COUNT: return syntax.Step.Function(syntax.Function(parse_selector(t.fields)))
+        raise ValueError('Invalid Preserves path function: ' + repr(t))
     if t == AXIS_VALUES: return syntax.Step.Axis(syntax.Axis.values())
     if t == AXIS_DESCENDANTS: return syntax.Step.Axis(syntax.Axis.descendants())
     if t == AXIS_MEMBER: return syntax.Step.Axis(syntax.Axis.at(next(tokens)))
@@ -88,11 +93,11 @@ def parse_step(tokens):
         return syntax.Step.Filter(syntax.Filter.regex(re_val))
     if t == FILTER_LABEL:
         label_lit = next(tokens)
-        return syntax.Step.Test(syntax.Predicate.Selector(syntax.Selector([
+        return syntax.Step.Filter(syntax.Filter.test(syntax.Predicate.Selector(syntax.Selector([
             syntax.Step.Axis(syntax.Axis.label()),
             syntax.Step.Filter(syntax.Filter.compare(
                 syntax.Comparison.eq(),
-                label_lit))])))
+                label_lit))]))))
     if t == TRANSFORM_REAL: return syntax.Step.Filter(syntax.Filter.real)
     if t == TRANSFORM_INT: return syntax.Step.Filter(syntax.Filter.int)
     if t == FILTER_BOOL: return kind_filter(syntax.ValueKind.Boolean())
@@ -181,6 +186,7 @@ def exec(self, v):
 
 @extend(syntax.Step.Axis)
 @extend(syntax.Step.Filter)
+@extend(syntax.Step.Function)
 def exec(self, v):
     return self.value.exec(v)
 
@@ -225,7 +231,7 @@ def exec(self, v):
 @extend(syntax.Axis.label)
 def exec(self, v):
     v = preserve(_unwrap(v))
-    return (v.label,) if isinstance(v, Record) else ()
+    return (v.key,) if isinstance(v, Record) else ()
 
 @extend(syntax.Axis.keys)
 def exec(self, v):
@@ -383,6 +389,10 @@ def exec(self, v):
 def exec(self, v):
     return (v,) if isinstance(v, Embedded) else ()
 
+@extend(syntax.Function)
+def exec(self, v):
+    return (len(self.selector.exec(v)),)
+
 if __name__ == '__main__':
     import sys
     sel = parse(sys.argv[1])

implementations/python/tests/test_path.py

@@ -0,0 +1,30 @@
+import unittest
+
+from preserves import *
+from preserves.path import parse
+
+class BasicPathTests(unittest.TestCase):
+    def test_identity(self):
+        self.assertEqual(parse('').exec(1), (1,))
+        self.assertEqual(parse('').exec([]), ([],))
+        self.assertEqual(parse('').exec(Record(Symbol('hi'), [])), (Record(Symbol('hi'), []),))
+
+    def test_children(self):
+        self.assertEqual(parse('/').exec([1, 2, 3]), (1, 2, 3))
+        self.assertEqual(parse('/').exec([1, [2], 3]), (1, [2], 3))
+        self.assertEqual(parse('/').exec(Record(Symbol('hi'), [1, [2], 3])), (1, [2], 3))
+
+    def test_label(self):
+        self.assertEqual(parse('.^').exec([1, 2, 3]), ())
+        self.assertEqual(parse('.^').exec([1, [2], 3]), ())
+        self.assertEqual(parse('.^').exec(Record(Symbol('hi'), [1, [2], 3])), (Symbol('hi'),))
+
+    def test_count(self):
+        self.assertEqual(parse('<count / ^ hi>').exec([ Record(Symbol('hi'), [1]),
+                                                        Record(Symbol('no'), [2]),
+                                                        Record(Symbol('hi'), [3]) ]),
+                         (2,))
+        self.assertEqual(parse('/ <count ^ hi>').exec([ Record(Symbol('hi'), [1]),
+                                                        Record(Symbol('no'), [2]),
+                                                        Record(Symbol('hi'), [3]) ]),
+                         (1, 0, 1))

implementations/rust/preserves-path/path.bin

@@ -1,5 +1,5 @@
-´³schema·³version‘³definitions·³Axis´³orµµ±values´³rec´³lit³values„´³tupleµ„„„„µ±descendants´³rec´³lit³descendants„´³tupleµ„„„„µ±at´³rec´³lit³at„´³tupleµ´³named³key³any„„„„„µ±label´³rec´³lit³label„´³tupleµ„„„„µ±keys´³rec´³lit³keys„´³tupleµ„„„„µ±length´³rec´³lit³length„´³tupleµ„„„„µ±annotations´³rec´³lit³annotations„´³tupleµ„„„„µ±embedded´³rec´³lit³embedded„´³tupleµ„„„„µ±parse´³rec´³lit³parse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„µ±unparse´³rec´³lit³unparse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„„„³Step´³orµµ±Axis´³refµ„³Axis„„µ±Filter´³refµ„³Filter„„„„³Filter´³orµµ±nop´³rec´³lit³nop„´³tupleµ„„„„µ±compare´³rec´³lit³compare„´³tupleµ´³named³op´³refµ„³
-Comparison„„´³named³literal³any„„„„„µ±regex´³rec´³lit³regex„´³tupleµ´³named³regex´³atom³String„„„„„„µ±test´³rec´³lit³test„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±real´³rec´³lit³real„´³tupleµ„„„„µ±int´³rec´³lit³int„´³tupleµ„„„„µ±kind´³rec´³lit³kind„´³tupleµ´³named³kind´³refµ„³	ValueKind„„„„„„„„³Selector´³seqof´³refµ„³Step„„³	Predicate´³orµµ±Selector´³refµ„³Selector„„µ±not´³rec´³lit³not„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±or´³rec´³lit³or„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„µ±and´³rec´³lit³and„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„„„³	ValueKind´³orµµ±Boolean´³lit³Boolean„„µ±Float´³lit³Float„„µ±Double´³lit³Double„„µ±
SignedInteger´³lit³
SignedInteger„„µ±String´³lit³String„„µ±
+´³schema·³version‘³definitions·³Axis´³orµµ±values´³rec´³lit³values„´³tupleµ„„„„µ±descendants´³rec´³lit³descendants„´³tupleµ„„„„µ±at´³rec´³lit³at„´³tupleµ´³named³key³any„„„„„µ±label´³rec´³lit³label„´³tupleµ„„„„µ±keys´³rec´³lit³keys„´³tupleµ„„„„µ±length´³rec´³lit³length„´³tupleµ„„„„µ±annotations´³rec´³lit³annotations„´³tupleµ„„„„µ±embedded´³rec´³lit³embedded„´³tupleµ„„„„µ±parse´³rec´³lit³parse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„µ±unparse´³rec´³lit³unparse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„„„³Step´³orµµ±Axis´³refµ„³Axis„„µ±Filter´³refµ„³Filter„„µ±Function´³refµ„³Function„„„„³Filter´³orµµ±nop´³rec´³lit³nop„´³tupleµ„„„„µ±compare´³rec´³lit³compare„´³tupleµ´³named³op´³refµ„³
+Comparison„„´³named³literal³any„„„„„µ±regex´³rec´³lit³regex„´³tupleµ´³named³regex´³atom³String„„„„„„µ±test´³rec´³lit³test„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±real´³rec´³lit³real„´³tupleµ„„„„µ±int´³rec´³lit³int„´³tupleµ„„„„µ±kind´³rec´³lit³kind„´³tupleµ´³named³kind´³refµ„³	ValueKind„„„„„„„„³Function´³rec´³lit³count„´³tupleµ´³named³selector´³refµ„³Selector„„„„„³Selector´³seqof´³refµ„³Step„„³	Predicate´³orµµ±Selector´³refµ„³Selector„„µ±not´³rec´³lit³not„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±or´³rec´³lit³or„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„µ±and´³rec´³lit³and„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„„„³	ValueKind´³orµµ±Boolean´³lit³Boolean„„µ±Float´³lit³Float„„µ±Double´³lit³Double„„µ±
SignedInteger´³lit³
SignedInteger„„µ±String´³lit³String„„µ±
 ByteString´³lit³
 ByteString„„µ±Symbol´³lit³Symbol„„µ±Record´³lit³Record„„µ±Sequence´³lit³Sequence„„µ±Set´³lit³Set„„µ±
 Dictionary´³lit³

implementations/rust/preserves-path/src/parse.rs

@@ -93,6 +93,22 @@ fn parse_step<'a>(env: &Env, tokens: &'a [IOValue]) -> Result<Option<(path::Step
         })), remainder)));
     }
 
+    match tokens[0].value().as_record(None) {
+        None => (),
+        Some(r) => match r.label().value().as_symbol() {
+            None => return Err(CompilationError::InvalidStep),
+            Some(t) => match t.as_str() {
+                "count" => return Ok(Some((
+                    path::Step::Function(Box::new(path::Function {
+                        selector: parse_selector(env, r.fields())?,
+                    })),
+                    remainder
+                ))),
+                _ => return Err(CompilationError::InvalidStep),
+            }
+        }
+    }
+
     match tokens[0].value().as_symbol() {
         None => return Err(CompilationError::InvalidStep),
         Some(t) => match t.as_str() {

implementations/rust/preserves-path/src/step.rs

@@ -95,15 +95,24 @@ struct KindStep {
     step: Node,
 }
 
+#[derive(Debug)]
+pub struct CountCollector {
+    count: usize,
+}
+
+#[derive(Debug)]
+struct CountStep {
+    step: Node,
+    counter: Node,
+}
+
 impl Node {
     fn new<S: Step + 'static>(s: S) -> Self {
         Node(Rc::new(RefCell::new(s)))
     }
 
     pub fn test(&self, ctxt: &mut Context, value: &IOValue) -> bool {
-        self.accept(ctxt, value);
-        self.finish();
-        !self.reset().is_empty()
+        !self.exec(ctxt, value).is_empty()
     }
 
     pub fn accept(&self, ctxt: &mut Context, value: &IOValue) {
@@ -145,6 +154,7 @@ impl StepMaker for path::Step {
         match self {
             path::Step::Axis(b) => (&**b).connect(step),
             path::Step::Filter(b) => (&**b).connect(step),
+            path::Step::Function(b) => (&**b).connect(step),
         }
     }
 }
@@ -418,3 +428,40 @@ impl path::Selector {
         Ok(self.compile()?.exec(ctxt, value))
     }
 }
+
+impl StepMaker for path::Function {
+    fn connect(&self, step: Node) -> Result<Node, CompilationError> {
+        // For now, there's just one function: `count`.
+        Ok(Node::new(CountStep { step, counter: self.selector.connect(CountCollector::new())? }))
+    }
+}
+
+impl CountCollector {
+    pub fn new() -> Node {
+        Node::new(CountCollector { count: 0 })
+    }
+}
+
+impl Step for CountCollector {
+    fn accept(&mut self, _ctxt: &mut Context, _value: &IOValue) {
+        self.count += 1
+    }
+
+    fn finish(&mut self) {
+    }
+
+    fn reset(&mut self) -> Vec<IOValue> {
+        let result = vec![IOValue::new(self.count)];
+        self.count = 0;
+        result
+    }
+}
+
+impl Step for CountStep {
+    fn accept(&mut self, ctxt: &mut Context, value: &IOValue) {
+        let count = &self.counter.exec(ctxt, value)[0];
+        self.step.accept(ctxt, count)
+    }
+
+    delegate_finish_and_reset!(self, self.step);
+}

path/path.bin

@@ -1,5 +1,5 @@
-´³schema·³version‘³definitions·³Axis´³orµµ±values´³rec´³lit³values„´³tupleµ„„„„µ±descendants´³rec´³lit³descendants„´³tupleµ„„„„µ±at´³rec´³lit³at„´³tupleµ´³named³key³any„„„„„µ±label´³rec´³lit³label„´³tupleµ„„„„µ±keys´³rec´³lit³keys„´³tupleµ„„„„µ±length´³rec´³lit³length„´³tupleµ„„„„µ±annotations´³rec´³lit³annotations„´³tupleµ„„„„µ±embedded´³rec´³lit³embedded„´³tupleµ„„„„µ±parse´³rec´³lit³parse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„µ±unparse´³rec´³lit³unparse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„„„³Step´³orµµ±Axis´³refµ„³Axis„„µ±Filter´³refµ„³Filter„„„„³Filter´³orµµ±nop´³rec´³lit³nop„´³tupleµ„„„„µ±compare´³rec´³lit³compare„´³tupleµ´³named³op´³refµ„³
-Comparison„„´³named³literal³any„„„„„µ±regex´³rec´³lit³regex„´³tupleµ´³named³regex´³atom³String„„„„„„µ±test´³rec´³lit³test„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±real´³rec´³lit³real„´³tupleµ„„„„µ±int´³rec´³lit³int„´³tupleµ„„„„µ±kind´³rec´³lit³kind„´³tupleµ´³named³kind´³refµ„³	ValueKind„„„„„„„„³Selector´³seqof´³refµ„³Step„„³	Predicate´³orµµ±Selector´³refµ„³Selector„„µ±not´³rec´³lit³not„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±or´³rec´³lit³or„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„µ±and´³rec´³lit³and„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„„„³	ValueKind´³orµµ±Boolean´³lit³Boolean„„µ±Float´³lit³Float„„µ±Double´³lit³Double„„µ±
SignedInteger´³lit³
SignedInteger„„µ±String´³lit³String„„µ±
+´³schema·³version‘³definitions·³Axis´³orµµ±values´³rec´³lit³values„´³tupleµ„„„„µ±descendants´³rec´³lit³descendants„´³tupleµ„„„„µ±at´³rec´³lit³at„´³tupleµ´³named³key³any„„„„„µ±label´³rec´³lit³label„´³tupleµ„„„„µ±keys´³rec´³lit³keys„´³tupleµ„„„„µ±length´³rec´³lit³length„´³tupleµ„„„„µ±annotations´³rec´³lit³annotations„´³tupleµ„„„„µ±embedded´³rec´³lit³embedded„´³tupleµ„„„„µ±parse´³rec´³lit³parse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„µ±unparse´³rec´³lit³unparse„´³tupleµ´³named³module´³seqof´³atom³Symbol„„„´³named³name´³atom³Symbol„„„„„„„„³Step´³orµµ±Axis´³refµ„³Axis„„µ±Filter´³refµ„³Filter„„µ±Function´³refµ„³Function„„„„³Filter´³orµµ±nop´³rec´³lit³nop„´³tupleµ„„„„µ±compare´³rec´³lit³compare„´³tupleµ´³named³op´³refµ„³
+Comparison„„´³named³literal³any„„„„„µ±regex´³rec´³lit³regex„´³tupleµ´³named³regex´³atom³String„„„„„„µ±test´³rec´³lit³test„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±real´³rec´³lit³real„´³tupleµ„„„„µ±int´³rec´³lit³int„´³tupleµ„„„„µ±kind´³rec´³lit³kind„´³tupleµ´³named³kind´³refµ„³	ValueKind„„„„„„„„³Function´³rec´³lit³count„´³tupleµ´³named³selector´³refµ„³Selector„„„„„³Selector´³seqof´³refµ„³Step„„³	Predicate´³orµµ±Selector´³refµ„³Selector„„µ±not´³rec´³lit³not„´³tupleµ´³named³pred´³refµ„³	Predicate„„„„„„µ±or´³rec´³lit³or„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„µ±and´³rec´³lit³and„´³tupleµ´³named³preds´³seqof´³refµ„³	Predicate„„„„„„„„„³	ValueKind´³orµµ±Boolean´³lit³Boolean„„µ±Float´³lit³Float„„µ±Double´³lit³Double„„µ±
SignedInteger´³lit³
SignedInteger„„µ±String´³lit³String„„µ±
 ByteString´³lit³
 ByteString„„µ±Symbol´³lit³Symbol„„µ±Record´³lit³Record„„µ±Sequence´³lit³Sequence„„µ±Set´³lit³Set„„µ±
 Dictionary´³lit³

path/path.prs

@@ -9,7 +9,7 @@ Predicate =
 / <and @preds [Predicate ...]>
 .
 
-Step = Axis / Filter .
+Step = Axis / Filter / Function .
 
 Axis =
 / <values>
@@ -41,3 +41,7 @@ ValueKind =
 / =Record / =Sequence / =Set / =Dictionary
 / =Embedded
 .
+
+Function =
+/ <count @selector Selector>
+.