From 15d503b396a3a7fb9280447c019c2a7795f62a27 Mon Sep 17 00:00:00 2001
From: Ziyang Hu <hu.ziyang@cantab.net>
Date: Sat, 27 Aug 2022 19:09:46 +0800
Subject: [PATCH] op 'to_float'

---
 README.md        |  2 +-
 src/data/expr.rs | 16 ++++++++++++++++
 src/data/json.rs | 39 ++++++++++++++++++++++++++++++++++-----
 3 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 0e2f55cc..33d3a241 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@
 * [ ] graph algorithms
   * [x] bfs
   * [x] dfs
-  * [ ] shortest path
+  * [ ] shortest path, SSSP
   * [ ] A*
   * [ ] Yen's k-shortest
   * [ ] all-pairs shortest path
diff --git a/src/data/expr.rs b/src/data/expr.rs
index a93e6dec..848a5b5e 100644
--- a/src/data/expr.rs
+++ b/src/data/expr.rs
@@ -3,6 +3,7 @@ use std::collections::{BTreeMap, BTreeSet};
 use std::fmt::{Debug, Formatter};
 use std::mem;
 use std::ops::{Div, Rem};
+use std::str::FromStr;
 
 use anyhow::{anyhow, bail, ensure, Result};
 use itertools::Itertools;
@@ -1501,6 +1502,20 @@ fn op_decode_base64(args: &[DataValue]) -> Result<DataValue> {
     }
 }
 
+define_op!(OP_TO_FLOAT, 1, false, false);
+fn op_to_float(args: &[DataValue]) -> Result<DataValue> {
+    Ok(match &args[0] {
+        DataValue::Number(n) => n.get_float().into(),
+        DataValue::String(t) => match t as &str {
+            "NAN" => f64::NAN.into(),
+            "INFINITY" => f64::INFINITY.into(),
+            "NEGATIVE_INFINITY" => f64::NEG_INFINITY.into(),
+            s => f64::from_str(s)?.into(),
+        },
+        v => bail!("'to_float' cannot be applied to {:?}", v),
+    })
+}
+
 pub(crate) fn get_op(name: &str) -> Option<&'static Op> {
     Some(match name {
         "list" => &OP_LIST,
@@ -1595,6 +1610,7 @@ pub(crate) fn get_op(name: &str) -> Option<&'static Op> {
         "chunks" => &OP_CHUNKS,
         "chunks_exact" => &OP_CHUNKS_EXACT,
         "windows" => &OP_WINDOWS,
+        "to_float" => &OP_TO_FLOAT,
         _ => return None,
     })
 }
diff --git a/src/data/json.rs b/src/data/json.rs
index 8032e521..14cfe229 100644
--- a/src/data/json.rs
+++ b/src/data/json.rs
@@ -63,7 +63,21 @@ impl From<DataValue> for JsonValue {
             DataValue::Null => JsonValue::Null,
             DataValue::Bool(b) => JsonValue::Bool(b),
             DataValue::Number(Number::Int(i)) => JsonValue::Number(i.into()),
-            DataValue::Number(Number::Float(f)) => json!(f),
+            DataValue::Number(Number::Float(f)) => {
+                if f.is_finite() {
+                    json!(f)
+                } else if f.is_nan() {
+                    json!(())
+                } else if f.is_infinite() {
+                    if f.is_sign_negative() {
+                        json!("NEGATIVE_INFINITY")
+                    } else {
+                        json!("INFINITY")
+                    }
+                } else {
+                    unreachable!()
+                }
+            }
             DataValue::String(t) => JsonValue::String(t.into()),
             DataValue::Bytes(bytes) => JsonValue::String(base64::encode(bytes)),
             DataValue::List(l) => {
@@ -77,10 +91,9 @@ impl From<DataValue> for JsonValue {
             }
             DataValue::Regex(r) => {
                 json!(r.0.as_str())
-            }
-            // DataValue::Map(m) => {
-            //     JsonValue::Array(m.into_iter().map(|(k, v)| json!([k, v])).collect())
-            // }
+            } // DataValue::Map(m) => {
+              //     JsonValue::Array(m.into_iter().map(|(k, v)| json!([k, v])).collect())
+              // }
         }
     }
 }
@@ -215,3 +228,19 @@ impl TryFrom<&'_ JsonValue> for TxId {
         Ok(TxId(v))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+    use crate::data::json::JsonValue;
+
+    use crate::data::value::DataValue;
+
+    #[test]
+    fn bad_values() {
+        println!("{}", json!(f64::INFINITY));
+        println!("{}", JsonValue::from(DataValue::from(f64::INFINITY)));
+        println!("{}", JsonValue::from(DataValue::from(f64::NEG_INFINITY)));
+        println!("{}", JsonValue::from(DataValue::from(f64::NAN)));
+    }
+}