Rename real to ~real, and add ~int to match

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

@@ -7,6 +7,7 @@ pub use crate::schemas::path;
 
 use num::bigint::BigInt;
 use num::traits::cast::ToPrimitive;
+use num::traits::cast::FromPrimitive;
 
 use preserves::value::AtomClass;
 use preserves::value::BinarySource;
@@ -303,6 +304,7 @@ impl StepMaker for path::Filter {
             path::Filter::Regex { regex } => Ok(Node::new(RegexStep { regex: regex::Regex::new(regex)?, step })),
             path::Filter::Test { pred } => Ok(Node::new(TestStep { pred: compile_predicate(&**pred)?, step })),
             path::Filter::Real => Ok(Node::new(RealStep { step })),
+            path::Filter::Int => Ok(Node::new(IntStep { step })),
             path::Filter::Kind { kind } => Ok(Node::new(KindStep {
                 kind: match &**kind {
                     path::ValueKind::Boolean => ValueClass::Atomic(AtomClass::Boolean),
@@ -411,6 +413,28 @@ impl Step for RealStep {
     delegate_finish_and_reset!(self, self.step);
 }
 
+#[derive(Debug)]
+struct IntStep {
+    step: Node,
+}
+
+impl Step for IntStep {
+    fn accept(&mut self, path: Rc<Path>, value: &IOValue) {
+        match value.value() {
+            Value::SignedInteger(_) => self.step.accept(path, value),
+            Value::Float(f) => if let Some(i) = BigInt::from_f32(f32::from(*f)) {
+                self.step.accept(path, &IOValue::new(i))
+            },
+            Value::Double(d) => if let Some(i) = BigInt::from_f64(f64::from(*d)) {
+                self.step.accept(path, &IOValue::new(i))
+            },
+            _ => (),
+        }
+    }
+
+    delegate_finish_and_reset!(self, self.step);
+}
+
 #[derive(Debug)]
 struct VecCollector {
     accumulator: Vec<IOValue>,
@@ -584,7 +608,8 @@ fn parse_step(tokens: &[IOValue]) -> Result<Option<(path::Step, &[IOValue])>, Co
                 })), remainder)))
             }
 
-            "real" => Ok(Some((path::Step::Filter(Box::new(path::Filter::Real)), remainder))),
+            "~real" => Ok(Some((path::Step::Filter(Box::new(path::Filter::Real)), remainder))),
+            "~int" => Ok(Some((path::Step::Filter(Box::new(path::Filter::Int)), remainder))),
 
             "bool" => Ok(Some((path::Step::from(path::ValueKind::Boolean), remainder))),
             "float" => Ok(Some((path::Step::from(path::ValueKind::Float), remainder))),

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„„„„„„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±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±
+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±
 ByteString´³lit³
 ByteString„„µ±Symbol´³lit³Symbol„„µ±Record´³lit³Record„„µ±Sequence´³lit³Sequence„„µ±Set´³lit³Set„„µ±
 Dictionary´³lit³

path/path.prs

@@ -28,6 +28,7 @@ Filter =
 / <regex @regex string>
 / <test @pred Predicate>
 / <real>
+/ <int>
 / <kind @kind ValueKind>
 .
 

preserves-path.md

@@ -79,10 +79,13 @@ Filters: narrow down a selection without moving
 
         ^ literal         ;; Matches a record having a the literal as its label -- equivalent to [.^ = literal]
 
-        real              ;; Promotes int and float to double, passes on double unchanged, rejects others
+        ~real             ;; Promotes int and float to double, passes on double unchanged, rejects others
                           ;; Out-of-range ints (too big or too small) become various double infinities
                           ;; Converting high-magnitude ints causes loss of precision
 
+        ~int              ;; Converts float and double to closest integer, where possible
+                          ;; NaN and infinities are rejected
+
         bool              ;; Type filters
         float
         double