Move Schema from mentat_db to mentat_core, improve API. (#290)

* Move Schema from mentat_db to mentat_core.
* Define SchemaMap in terms of Entid, not i64.
* Add Schema::{is_attribute,identifies_attribute}.
* Add pointer to #291.
* Don't pass around 64-bit pointers to 64-bit integers.

core/src/lib.rs

@@ -9,6 +9,8 @@
 // specific language governing permissions and limitations under the License.
 
 extern crate ordered_float;
+
+use std::collections::BTreeMap;
 use self::ordered_float::OrderedFloat;
 
 /// Core types defining a Mentat knowledge base.
@@ -173,6 +175,64 @@ impl Default for Attribute {
     }
 }
 
+/// Map `String` idents (`:db/ident`) to positive integer entids (`1`).
+/// TODO: these should all be parsed into NamespacedKeywords on entry. #291.
+pub type IdentMap = BTreeMap<String, Entid>;
+
+/// Map positive integer entids (`1`) to `String` idents (`:db/ident`).
+pub type EntidMap = BTreeMap<Entid, String>;
+
+/// Map attribute entids to `Attribute` instances.
+pub type SchemaMap = BTreeMap<Entid, Attribute>;
+
+/// Represents a Mentat schema.
+///
+/// Maintains the mapping between string idents and positive integer entids; and exposes the schema
+/// flags associated to a given entid (equivalently, ident).
+///
+/// TODO: consider a single bi-directional map instead of separate ident->entid and entid->ident
+/// maps.
+#[derive(Clone, Debug, Default, Eq, Hash, Ord, PartialOrd, PartialEq)]
+pub struct Schema {
+    /// Map entid->ident.
+    ///
+    /// Invariant: is the inverse map of `ident_map`.
+    pub entid_map: EntidMap,
+
+    /// Map ident->entid.
+    ///
+    /// Invariant: is the inverse map of `entid_map`.
+    pub ident_map: IdentMap,
+
+    /// Map entid->attribute flags.
+    ///
+    /// Invariant: key-set is the same as the key-set of `entid_map` (equivalently, the value-set of
+    /// `ident_map`).
+    pub schema_map: SchemaMap,
+}
+
+impl Schema {
+    pub fn get_ident(&self, x: Entid) -> Option<&String> {
+        self.entid_map.get(&x)
+    }
+
+    pub fn get_entid(&self, x: &String) -> Option<Entid> {
+        self.ident_map.get(x).map(|x| *x)
+    }
+
+    pub fn attribute_for_entid(&self, x: Entid) -> Option<&Attribute> {
+        self.schema_map.get(&x)
+    }
+
+    pub fn is_attribute(&self, x: Entid) -> bool {
+        self.schema_map.contains_key(&x)
+    }
+
+    pub fn identifies_attribute(&self, x: &String) -> bool {
+        self.get_entid(x).map(|e| self.is_attribute(e)).unwrap_or(false)
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

db/src/bootstrap.rs

@@ -18,8 +18,13 @@ use entids;
 use db::TypedSQLValue;
 use mentat_tx::entities::Entity;
 use mentat_tx_parser;
-use mentat_core::TypedValue;
+use mentat_core::{
-use types::{IdentMap, Partition, PartitionMap, Schema};
+    IdentMap,
+    Schema,
+    TypedValue,
+};
+use schema::SchemaBuilding;
+use types::{Partition, PartitionMap};
 use values;
 
 /// The first transaction ID applied to the knowledge base.

db/src/db.rs

@@ -23,10 +23,20 @@ use ::{repeat_values, to_namespaced_keyword};
 use bootstrap;
 use edn::types::Value;
 use entids;
+use mentat_core::{
+    Attribute,
+    AttributeBitFlags,
+    Entid,
+    IdentMap,
+    Schema,
+    TypedValue,
+    ValueType,
+};
 use mentat_tx::entities as entmod;
 use mentat_tx::entities::{Entity, OpType};
 use errors::{ErrorKind, Result, ResultExt};
-use types::{Attribute, AttributeBitFlags, DB, Entid, IdentMap, Partition, PartitionMap, Schema, TypedValue, ValueType};
+use types::{DB, Partition, PartitionMap};
+use schema::SchemaBuilding;
 
 pub fn new_connection<T>(uri: T) -> rusqlite::Result<rusqlite::Connection> where T: AsRef<Path> {
     let conn = match uri.as_ref().to_string_lossy().len() {
@@ -446,7 +456,7 @@ impl DB {
                 (&ValueType::Keyword, tv @ TypedValue::Keyword(_)) => Ok(tv),
                 // Ref coerces a little: we interpret some things depending on the schema as a Ref.
                 (&ValueType::Ref, TypedValue::Long(x)) => Ok(TypedValue::Ref(x)),
-                (&ValueType::Ref, TypedValue::Keyword(ref x)) => self.schema.require_entid(&x.to_string()).map(|&entid| TypedValue::Ref(entid)),
+                (&ValueType::Ref, TypedValue::Keyword(ref x)) => self.schema.require_entid(&x.to_string()).map(|entid| TypedValue::Ref(entid)),
                 // Otherwise, we have a type mismatch.
                 (value_type, _) => bail!(ErrorKind::BadEDNValuePair(value.clone(), value_type.clone())),
             }
@@ -535,7 +545,7 @@ impl DB {
                                    /* added0 */ bool,
                                    /* flags0 */ u8)>> = chunk.map(|&(e, a, ref typed_value, added)| {
                 count += 1;
-                let attribute: &Attribute = self.schema.require_attribute_for_entid(&a)?;
+                let attribute: &Attribute = self.schema.require_attribute_for_entid(a)?;
 
                 // Now we can represent the typed value as an SQL value.
                 let (value, value_type_tag): (ToSqlOutput, i32) = typed_value.to_sql_value_pair();
@@ -725,15 +735,15 @@ impl DB {
 
                     let e: i64 = match e_ {
                         &entmod::Entid::Entid(ref e__) => *e__,
-                        &entmod::Entid::Ident(ref e__) => *self.schema.require_entid(&e__.to_string())?,
+                        &entmod::Entid::Ident(ref e__) => self.schema.require_entid(&e__.to_string())?,
                     };
 
                     let a: i64 = match a_ {
                         &entmod::Entid::Entid(ref a__) => *a__,
-                        &entmod::Entid::Ident(ref a__) => *self.schema.require_entid(&a__.to_string())?,
+                        &entmod::Entid::Ident(ref a__) => self.schema.require_entid(&a__.to_string())?,
                     };
 
-                    let attribute: &Attribute = self.schema.require_attribute_for_entid(&a)?;
+                    let attribute: &Attribute = self.schema.require_attribute_for_entid(a)?;
                     if attribute.fulltext {
                         bail!(ErrorKind::NotYetImplemented(format!("Transacting :db/fulltext entities is not yet implemented: {:?}", entity)))
                     }
@@ -760,15 +770,15 @@ impl DB {
 
                     let e: i64 = match e_ {
                         &entmod::Entid::Entid(ref e__) => *e__,
-                        &entmod::Entid::Ident(ref e__) => *self.schema.require_entid(&e__.to_string())?,
+                        &entmod::Entid::Ident(ref e__) => self.schema.require_entid(&e__.to_string())?,
                     };
 
                     let a: i64 = match a_ {
                         &entmod::Entid::Entid(ref a__) => *a__,
-                        &entmod::Entid::Ident(ref a__) => *self.schema.require_entid(&a__.to_string())?,
+                        &entmod::Entid::Ident(ref a__) => self.schema.require_entid(&a__.to_string())?,
                     };
 
-                    let attribute: &Attribute = self.schema.require_attribute_for_entid(&a)?;
+                    let attribute: &Attribute = self.schema.require_attribute_for_entid(a)?;
                     if attribute.fulltext {
                         bail!(ErrorKind::NotYetImplemented(format!("Transacting :db/fulltext entities is not yet implemented: {:?}", entity)))
                     }

db/src/debug.rs

@@ -107,7 +107,7 @@ impl Transactions {
 
 /// Convert a numeric entid to an ident `Entid` if possible, otherwise a numeric `Entid`.
 fn to_entid(db: &DB, entid: i64) -> Entid {
-    db.schema.get_ident(&entid).and_then(|ident| to_namespaced_keyword(&ident)).map_or(Entid::Entid(entid), Entid::Ident)
+    db.schema.get_ident(entid).and_then(|ident| to_namespaced_keyword(&ident)).map_or(Entid::Entid(entid), Entid::Ident)
 }
 
 /// Return the set of datoms in the store, ordered by (e, a, v, tx), but not including any datoms of

db/src/schema.rs

@@ -12,7 +12,16 @@
 
 use entids;
 use errors::*;
-use types::{Attribute, Entid, EntidMap, IdentMap, Schema, SchemaMap, TypedValue, ValueType};
+use mentat_core::{
+    Attribute,
+    Entid,
+    EntidMap,
+    IdentMap,
+    Schema,
+    SchemaMap,
+    TypedValue,
+    ValueType,
+};
 
 /// Return `Ok(())` if `schema_map` defines a valid Mentat schema.
 fn validate_schema_map(entid_map: &EntidMap, schema_map: &SchemaMap) -> Result<()> {
@@ -40,33 +49,30 @@ fn validate_schema_map(entid_map: &EntidMap, schema_map: &SchemaMap) -> Result<(
     Ok(())
 }
 
-impl Schema {
+pub trait SchemaBuilding {
-    pub fn get_ident(&self, x: &Entid) -> Option<&String> {
+    fn require_ident(&self, entid: Entid) -> Result<&String>;
-        self.entid_map.get(x)
+    fn require_entid(&self, ident: &String) -> Result<Entid>;
+    fn require_attribute_for_entid(&self, entid: Entid) -> Result<&Attribute>;
+    fn from_ident_map_and_schema_map(ident_map: IdentMap, schema_map: SchemaMap) -> Result<Schema>;
+    fn from_ident_map_and_triples<U>(ident_map: IdentMap, assertions: U) -> Result<Schema>
+        where U: IntoIterator<Item=(String, String, TypedValue)>;
+}
+
+impl SchemaBuilding for Schema {
+    fn require_ident(&self, entid: Entid) -> Result<&String> {
+        self.get_ident(entid).ok_or(ErrorKind::UnrecognizedEntid(entid).into())
     }
 
-    pub fn get_entid(&self, x: &String) -> Option<&Entid> {
+    fn require_entid(&self, ident: &String) -> Result<Entid> {
-        self.ident_map.get(x)
-    }
-
-    pub fn attribute_for_entid(&self, x: &Entid) -> Option<&Attribute> {
-        self.schema_map.get(x)
-    }
-
-    pub fn require_ident(&self, entid: &Entid) -> Result<&String> {
-        self.get_ident(&entid).ok_or(ErrorKind::UnrecognizedEntid(*entid).into())
-    }
-
-    pub fn require_entid(&self, ident: &String) -> Result<&Entid> {
         self.get_entid(&ident).ok_or(ErrorKind::UnrecognizedIdent(ident.clone()).into())
     }
 
-    pub fn require_attribute_for_entid(&self, entid: &Entid) -> Result<&Attribute> {
+    fn require_attribute_for_entid(&self, entid: Entid) -> Result<&Attribute> {
-        self.attribute_for_entid(entid).ok_or(ErrorKind::UnrecognizedEntid(*entid).into())
+        self.attribute_for_entid(entid).ok_or(ErrorKind::UnrecognizedEntid(entid).into())
     }
 
     /// Create a valid `Schema` from the constituent maps.
-    pub fn from(ident_map: IdentMap, schema_map: SchemaMap) -> Result<Schema> {
+    fn from_ident_map_and_schema_map(ident_map: IdentMap, schema_map: SchemaMap) -> Result<Schema> {
         let entid_map: EntidMap = ident_map.iter().map(|(k, v)| (v.clone(), k.clone())).collect();
 
         validate_schema_map(&entid_map, &schema_map)?;
@@ -79,7 +85,7 @@ impl Schema {
     }
 
     /// Turn vec![(String(:ident), String(:key), TypedValue(:value)), ...] into a Mentat `Schema`.
-    pub fn from_ident_map_and_triples<U>(ident_map: IdentMap, assertions: U) -> Result<Schema>
+    fn from_ident_map_and_triples<U>(ident_map: IdentMap, assertions: U) -> Result<Schema>
         where U: IntoIterator<Item=(String, String, TypedValue)>{
         let mut schema_map = SchemaMap::new();
         for (ref symbolic_ident, ref symbolic_attr, ref value) in assertions.into_iter() {
@@ -167,6 +173,6 @@ impl Schema {
             }
         };
 
-        Schema::from(ident_map.clone(), schema_map)
+        Schema::from_ident_map_and_schema_map(ident_map.clone(), schema_map)
     }
 }

db/src/types.rs

@@ -20,6 +20,7 @@ pub use self::mentat_core::{
     TypedValue,
     Attribute,
     AttributeBitFlags,
+    Schema,
 };
 
 /// Represents one partition of the entid space.
@@ -40,40 +41,6 @@ impl Partition {
 
 /// Map partition names to `Partition` instances.
 pub type PartitionMap = BTreeMap<String, Partition>;
-/// Map `String` idents (`:db/ident`) to positive integer entids (`1`).
-pub type IdentMap = BTreeMap<String, Entid>;
-
-/// Map positive integer entids (`1`) to `String` idents (`:db/ident`).
-pub type EntidMap = BTreeMap<Entid, String>;
-
-/// Map attribute entids to `Attribute` instances.
-pub type SchemaMap = BTreeMap<i64, Attribute>;
-
-/// Represents a Mentat schema.
-///
-/// Maintains the mapping between string idents and positive integer entids; and exposes the schema
-/// flags associated to a given entid (equivalently, ident).
-///
-/// TODO: consider a single bi-directional map instead of separate ident->entid and entid->ident
-/// maps.
-#[derive(Clone,Debug,Default,Eq,Hash,Ord,PartialOrd,PartialEq)]
-pub struct Schema {
-    /// Map entid->ident.
-    ///
-    /// Invariant: is the inverse map of `ident_map`.
-    pub entid_map: EntidMap,
-
-    /// Map ident->entid.
-    ///
-    /// Invariant: is the inverse map of `entid_map`.
-    pub ident_map: IdentMap,
-
-    /// Map entid->attribute flags.
-    ///
-    /// Invariant: key-set is the same as the key-set of `entid_map` (equivalently, the value-set of
-    /// `ident_map`).
-    pub schema_map: SchemaMap,
-}
 
 /// Represents the metadata required to query from, or apply transactions to, a Mentat store.
 ///