2017-01-04 13:09:12 +00:00
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// Copyright 2016 Mozilla
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
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// this file except in compliance with the License. You may obtain a copy of the
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// License at http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed
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// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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// CONDITIONS OF ANY KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations under the License.
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2017-01-25 22:06:19 +00:00
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///! This module defines some core types that support find expressions: sources,
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///! variables, expressions, etc.
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///! These are produced as 'fuel' by the query parser, consumed by the query
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///! translator and executor.
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///!
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///! Many of these types are defined as simple structs that are little more than
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///! a richer type alias: a variable, for example, is really just a fancy kind
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///! of string.
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///!
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///! At some point in the future, we might consider reducing copying and memory
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///! usage by recasting all of these string-holding structs and enums in terms
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///! of string references, with those references being slices of some parsed
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///! input query string, and valid for the lifetime of that string.
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///!
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///! For now, for the sake of simplicity, all of these strings are heap-allocated.
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///!
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///! Furthermore, we might cut out some of the chaff here: each time a 'tagged'
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///! type is used within an enum, we have an opportunity to simplify and use the
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///! inner type directly in conjunction with matching on the enum. Before diving
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///! deeply into this it's worth recognizing that this loss of 'sovereignty' is
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///! a tradeoff against well-typed function signatures and other such boundaries.
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extern crate edn;
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2017-02-10 00:59:35 +00:00
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extern crate mentat_core;
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2017-01-25 22:06:19 +00:00
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2017-03-24 20:09:32 +00:00
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use std::collections::BTreeSet;
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2017-02-16 15:16:04 +00:00
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use std::fmt;
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2017-02-04 00:51:57 +00:00
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use edn::{BigInt, OrderedFloat};
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pub use edn::{NamespacedKeyword, PlainSymbol};
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2017-02-10 00:59:35 +00:00
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use mentat_core::TypedValue;
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2017-01-25 22:06:19 +00:00
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pub type SrcVarName = String; // Do not include the required syntactic '$'.
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2017-02-16 15:16:04 +00:00
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#[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
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2017-01-25 22:06:19 +00:00
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pub struct Variable(pub PlainSymbol);
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2017-02-01 22:51:02 +00:00
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pub trait FromValue<T> {
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fn from_value(v: &edn::Value) -> Option<T>;
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}
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/// If the provided EDN value is a PlainSymbol beginning with '?', return
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/// it wrapped in a Variable. If not, return None.
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impl FromValue<Variable> for Variable {
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fn from_value(v: &edn::Value) -> Option<Variable> {
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if let edn::Value::PlainSymbol(ref s) = *v {
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Variable::from_symbol(s)
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} else {
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None
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}
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}
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}
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impl Variable {
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2017-02-03 02:32:00 +00:00
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pub fn from_symbol(sym: &PlainSymbol) -> Option<Variable> {
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2017-02-01 22:51:02 +00:00
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if sym.is_var_symbol() {
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Some(Variable(sym.clone()))
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} else {
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None
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}
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}
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2017-02-16 15:16:04 +00:00
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}
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impl fmt::Debug for Variable {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "var({})", self.0)
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}
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2017-02-01 22:51:02 +00:00
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}
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2017-03-16 14:44:56 +00:00
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#[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
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pub struct PredicateFn(pub PlainSymbol);
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impl FromValue<PredicateFn> for PredicateFn {
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fn from_value(v: &edn::Value) -> Option<PredicateFn> {
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if let edn::Value::PlainSymbol(ref s) = *v {
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PredicateFn::from_symbol(s)
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} else {
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None
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}
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}
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}
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impl PredicateFn {
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pub fn from_symbol(sym: &PlainSymbol) -> Option<PredicateFn> {
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// TODO: validate the acceptable set of function names.
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Some(PredicateFn(sym.clone()))
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}
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}
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2017-02-01 22:51:02 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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2017-01-25 22:06:19 +00:00
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pub enum SrcVar {
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DefaultSrc,
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NamedSrc(SrcVarName),
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}
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2017-02-01 22:51:02 +00:00
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impl FromValue<SrcVar> for SrcVar {
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fn from_value(v: &edn::Value) -> Option<SrcVar> {
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if let edn::Value::PlainSymbol(ref s) = *v {
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SrcVar::from_symbol(s)
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} else {
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None
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}
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}
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}
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impl SrcVar {
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pub fn from_symbol(sym: &PlainSymbol) -> Option<SrcVar> {
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if sym.is_src_symbol() {
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Some(SrcVar::NamedSrc(sym.plain_name().to_string()))
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} else {
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None
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}
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}
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}
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2017-01-25 22:06:19 +00:00
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/// These are the scalar values representable in EDN.
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2017-02-03 02:32:00 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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2017-01-25 22:06:19 +00:00
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pub enum NonIntegerConstant {
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Boolean(bool),
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BigInteger(BigInt),
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Float(OrderedFloat<f64>),
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Text(String),
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}
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2017-02-10 00:59:35 +00:00
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impl NonIntegerConstant {
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pub fn into_typed_value(self) -> TypedValue {
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match self {
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NonIntegerConstant::BigInteger(_) => unimplemented!(), // TODO: #280.
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NonIntegerConstant::Boolean(v) => TypedValue::Boolean(v),
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NonIntegerConstant::Float(v) => TypedValue::Double(v),
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NonIntegerConstant::Text(v) => TypedValue::String(v),
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}
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}
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}
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2017-03-16 14:44:56 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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2017-01-25 22:06:19 +00:00
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pub enum FnArg {
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Variable(Variable),
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SrcVar(SrcVar),
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EntidOrInteger(i64),
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Ident(NamespacedKeyword),
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Constant(NonIntegerConstant),
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}
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2017-03-16 14:44:56 +00:00
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impl FromValue<FnArg> for FnArg {
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fn from_value(v: &edn::Value) -> Option<FnArg> {
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// TODO: support SrcVars.
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Variable::from_value(v)
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.and_then(|v| Some(FnArg::Variable(v)))
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.or_else(||
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match v {
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&edn::Value::Integer(i) => Some(FnArg::EntidOrInteger(i)),
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2017-03-16 19:23:48 +00:00
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&edn::Value::Float(f) => Some(FnArg::Constant(NonIntegerConstant::Float(f))),
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2017-03-16 14:44:56 +00:00
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_ => unimplemented!(),
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})
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}
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}
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2017-01-25 22:06:19 +00:00
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/// e, a, tx can't be values -- no strings, no floats -- and so
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/// they can only be variables, entity IDs, ident keywords, or
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/// placeholders.
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/// This encoding allows us to represent integers that aren't
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/// entity IDs. That'll get filtered out in the context of the
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/// database.
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2017-02-03 02:32:00 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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2017-01-25 22:06:19 +00:00
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pub enum PatternNonValuePlace {
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Placeholder,
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Variable(Variable),
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2017-02-03 02:32:00 +00:00
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Entid(i64), // Will always be +ve. See #190.
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2017-01-25 22:06:19 +00:00
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Ident(NamespacedKeyword),
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}
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2017-02-03 02:32:00 +00:00
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impl PatternNonValuePlace {
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// I think we'll want move variants, so let's leave these here for now.
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#[allow(dead_code)]
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fn into_pattern_value_place(self) -> PatternValuePlace {
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match self {
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PatternNonValuePlace::Placeholder => PatternValuePlace::Placeholder,
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PatternNonValuePlace::Variable(x) => PatternValuePlace::Variable(x),
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PatternNonValuePlace::Entid(x) => PatternValuePlace::EntidOrInteger(x),
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PatternNonValuePlace::Ident(x) => PatternValuePlace::IdentOrKeyword(x),
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}
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}
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fn to_pattern_value_place(&self) -> PatternValuePlace {
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match *self {
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PatternNonValuePlace::Placeholder => PatternValuePlace::Placeholder,
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PatternNonValuePlace::Variable(ref x) => PatternValuePlace::Variable(x.clone()),
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PatternNonValuePlace::Entid(x) => PatternValuePlace::EntidOrInteger(x),
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PatternNonValuePlace::Ident(ref x) => PatternValuePlace::IdentOrKeyword(x.clone()),
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}
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}
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}
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impl FromValue<PatternNonValuePlace> for PatternNonValuePlace {
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fn from_value(v: &edn::Value) -> Option<PatternNonValuePlace> {
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match v {
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&edn::Value::Integer(x) => if x >= 0 {
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Some(PatternNonValuePlace::Entid(x))
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} else {
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None
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},
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&edn::Value::PlainSymbol(ref x) => if x.0.as_str() == "_" {
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Some(PatternNonValuePlace::Placeholder)
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} else {
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if let Some(v) = Variable::from_symbol(x) {
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Some(PatternNonValuePlace::Variable(v))
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} else {
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None
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}
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},
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&edn::Value::NamespacedKeyword(ref x) =>
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Some(PatternNonValuePlace::Ident(x.clone())),
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_ => None,
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}
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}
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}
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2017-02-04 00:52:03 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub enum IdentOrEntid {
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Ident(NamespacedKeyword),
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Entid(i64),
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}
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2017-01-25 22:06:19 +00:00
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/// The `v` part of a pattern can be much broader: it can represent
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/// integers that aren't entity IDs (particularly negative integers),
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/// strings, and all the rest. We group those under `Constant`.
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2017-02-03 02:32:00 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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2017-01-25 22:06:19 +00:00
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pub enum PatternValuePlace {
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Placeholder,
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Variable(Variable),
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EntidOrInteger(i64),
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2017-02-03 02:32:00 +00:00
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IdentOrKeyword(NamespacedKeyword),
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2017-01-25 22:06:19 +00:00
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Constant(NonIntegerConstant),
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}
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2017-02-03 02:32:00 +00:00
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impl FromValue<PatternValuePlace> for PatternValuePlace {
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fn from_value(v: &edn::Value) -> Option<PatternValuePlace> {
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match v {
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&edn::Value::Integer(x) =>
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Some(PatternValuePlace::EntidOrInteger(x)),
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&edn::Value::PlainSymbol(ref x) if x.0.as_str() == "_" =>
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Some(PatternValuePlace::Placeholder),
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&edn::Value::PlainSymbol(ref x) if x.is_var_symbol() =>
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Some(PatternValuePlace::Variable(Variable(x.clone()))),
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&edn::Value::NamespacedKeyword(ref x) =>
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Some(PatternValuePlace::IdentOrKeyword(x.clone())),
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&edn::Value::Boolean(x) =>
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Some(PatternValuePlace::Constant(NonIntegerConstant::Boolean(x))),
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&edn::Value::Float(x) =>
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Some(PatternValuePlace::Constant(NonIntegerConstant::Float(x))),
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&edn::Value::BigInteger(ref x) =>
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Some(PatternValuePlace::Constant(NonIntegerConstant::BigInteger(x.clone()))),
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&edn::Value::Text(ref x) =>
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Some(PatternValuePlace::Constant(NonIntegerConstant::Text(x.clone()))),
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_ => None,
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}
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}
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}
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impl PatternValuePlace {
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// I think we'll want move variants, so let's leave these here for now.
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#[allow(dead_code)]
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fn into_pattern_non_value_place(self) -> Option<PatternNonValuePlace> {
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match self {
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PatternValuePlace::Placeholder => Some(PatternNonValuePlace::Placeholder),
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PatternValuePlace::Variable(x) => Some(PatternNonValuePlace::Variable(x)),
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PatternValuePlace::EntidOrInteger(x) => if x >= 0 {
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Some(PatternNonValuePlace::Entid(x))
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} else {
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None
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},
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PatternValuePlace::IdentOrKeyword(x) => Some(PatternNonValuePlace::Ident(x)),
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PatternValuePlace::Constant(_) => None,
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}
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}
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fn to_pattern_non_value_place(&self) -> Option<PatternNonValuePlace> {
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match *self {
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PatternValuePlace::Placeholder => Some(PatternNonValuePlace::Placeholder),
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PatternValuePlace::Variable(ref x) => Some(PatternNonValuePlace::Variable(x.clone())),
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PatternValuePlace::EntidOrInteger(x) => if x >= 0 {
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Some(PatternNonValuePlace::Entid(x))
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} else {
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None
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},
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PatternValuePlace::IdentOrKeyword(ref x) => Some(PatternNonValuePlace::Ident(x.clone())),
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PatternValuePlace::Constant(_) => None,
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}
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}
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}
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2017-01-25 22:06:19 +00:00
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/*
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pub enum PullPattern {
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Constant(Constant),
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Variable(Variable),
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}
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pub struct Pull {
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pub src: SrcVar,
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pub var: Variable,
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pub pattern: PullPattern, // Constant, variable, or plain variable.
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}
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*/
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/*
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pub struct Aggregate {
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pub fn_name: String,
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pub args: Vec<FnArg>,
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}
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*/
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#[derive(Clone,Debug,Eq,PartialEq)]
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pub enum Element {
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Variable(Variable),
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// Aggregate(Aggregate), // TODO
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// Pull(Pull), // TODO
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}
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/// A definition of the first part of a find query: the
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/// `[:find ?foo ?bar…]` bit.
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///
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/// There are four different kinds of find specs, allowing you to query for
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/// a single value, a collection of values from different entities, a single
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/// tuple (relation), or a collection of tuples.
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///
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/// Examples:
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///
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/// ```rust
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/// # extern crate edn;
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/// # extern crate mentat_query;
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/// # use edn::PlainSymbol;
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/// # use mentat_query::{Element, FindSpec, Variable};
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///
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/// # fn main() {
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///
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/// let elements = vec![
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/// Element::Variable(Variable(PlainSymbol("?foo".to_string()))),
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/// Element::Variable(Variable(PlainSymbol("?bar".to_string()))),
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/// ];
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/// let rel = FindSpec::FindRel(elements);
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///
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/// if let FindSpec::FindRel(elements) = rel {
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/// assert_eq!(2, elements.len());
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/// }
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///
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/// # }
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/// ```
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///
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#[derive(Clone,Debug,Eq,PartialEq)]
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pub enum FindSpec {
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/// Returns an array of arrays.
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FindRel(Vec<Element>),
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/// Returns an array of scalars, usually homogeneous.
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/// This is equivalent to mapping over the results of a `FindRel`,
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/// returning the first value of each.
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FindColl(Element),
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/// Returns a single tuple: a heterogeneous array of scalars. Equivalent to
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/// taking the first result from a `FindRel`.
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FindTuple(Vec<Element>),
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/// Returns a single scalar value. Equivalent to taking the first result
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/// from a `FindColl`.
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FindScalar(Element),
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}
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/// Returns true if the provided `FindSpec` returns at most one result.
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2017-03-06 22:40:10 +00:00
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impl FindSpec {
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pub fn is_unit_limited(&self) -> bool {
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use FindSpec::*;
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match self {
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&FindScalar(..) => true,
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&FindTuple(..) => true,
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&FindRel(..) => false,
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&FindColl(..) => false,
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}
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2017-01-25 22:06:19 +00:00
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}
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2017-03-06 22:40:10 +00:00
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pub fn expected_column_count(&self) -> usize {
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use FindSpec::*;
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match self {
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&FindScalar(..) => 1,
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&FindColl(..) => 1,
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&FindTuple(ref elems) | &FindRel(ref elems) => elems.len(),
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}
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}
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/// Returns true if the provided `FindSpec` cares about distinct results.
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///
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/// I use the words "cares about" because find is generally defined in terms of producing distinct
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/// results at the Datalog level.
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///
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/// Two of the find specs (scalar and tuple) produce only a single result. Those don't need to be
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/// run with `SELECT DISTINCT`, because we're only consuming a single result. Those queries will be
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/// run with `LIMIT 1`.
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///
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/// Additionally, some projections cannot produce duplicate results: `[:find (max ?x) …]`, for
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/// example.
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///
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/// This function gives us the hook to add that logic when we're ready.
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///
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/// Beyond this, `DISTINCT` is not always needed. For example, in some kinds of accumulation or
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/// sampling projections we might not need to do it at the SQL level because we're consuming into
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/// a dupe-eliminating data structure like a Set, or we know that a particular query cannot produce
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/// duplicate results.
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pub fn requires_distinct(&self) -> bool {
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!self.is_unit_limited()
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}
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2017-01-25 22:06:19 +00:00
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}
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// Note that the "implicit blank" rule applies.
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// A pattern with a reversed attribute — :foo/_bar — is reversed
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// at the point of parsing. These `Pattern` instances only represent
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// one direction.
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2017-02-03 02:32:00 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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2017-01-25 22:06:19 +00:00
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pub struct Pattern {
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2017-02-03 02:32:00 +00:00
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pub source: Option<SrcVar>,
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pub entity: PatternNonValuePlace,
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pub attribute: PatternNonValuePlace,
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pub value: PatternValuePlace,
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pub tx: PatternNonValuePlace,
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}
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impl Pattern {
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pub fn new(src: Option<SrcVar>,
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e: PatternNonValuePlace,
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a: PatternNonValuePlace,
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v: PatternValuePlace,
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tx: PatternNonValuePlace) -> Option<Pattern> {
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let aa = a.clone(); // Too tired of fighting borrow scope for now.
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if let PatternNonValuePlace::Ident(ref k) = aa {
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if k.is_backward() {
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// e and v have different types; we must convert them.
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// Not every parseable value is suitable for the entity field!
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// As such, this is a failable constructor.
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let e_v = e.to_pattern_value_place();
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if let Some(v_e) = v.to_pattern_non_value_place() {
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return Some(Pattern {
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source: src,
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entity: v_e,
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attribute: PatternNonValuePlace::Ident(k.to_reversed()),
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value: e_v,
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tx: tx,
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});
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} else {
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return None;
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}
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}
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}
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Some(Pattern {
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source: src,
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entity: e,
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attribute: a,
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value: v,
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tx: tx,
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})
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}
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2017-01-25 22:06:19 +00:00
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}
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2017-03-16 14:44:56 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub struct Predicate {
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pub operator: PlainSymbol,
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pub args: Vec<FnArg>,
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}
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2017-02-03 02:32:00 +00:00
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2017-03-23 20:10:44 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub enum UnifyVars {
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/// `Implicit` means the variables in an `or` or `not` are derived from the enclosed pattern.
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/// DataScript regards these vars as 'free': these variables don't need to be bound by the
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/// enclosing environment.
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///
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/// Datomic's documentation implies that all implicit variables are required:
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///
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/// > Datomic will attempt to push the or clause down until all necessary variables are bound,
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/// > and will throw an exception if that is not possible.
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///
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/// but that would render top-level `or` expressions (as used in Datomic's own examples!)
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/// impossible, so we assume that this is an error in the documentation.
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///
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/// All contained 'arms' in an `or` with implicit variables must bind the same vars.
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Implicit,
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/// `Explicit` means the variables in an `or-join` or `not-join` are explicitly listed,
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/// specified with `required-vars` syntax.
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///
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/// DataScript parses these as free, but allows (incorrectly) the use of more complicated
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/// `rule-vars` syntax.
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///
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/// Only the named variables will be unified with the enclosing query.
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///
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/// Every 'arm' in an `or-join` must mention the entire set of explicit vars.
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Explicit(Vec<Variable>),
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}
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2017-03-28 03:53:08 +00:00
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impl WhereClause {
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pub fn is_pattern(&self) -> bool {
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match self {
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&WhereClause::Pattern(_) => true,
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_ => false,
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}
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}
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}
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2017-03-23 20:10:44 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub enum OrWhereClause {
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Clause(WhereClause),
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And(Vec<WhereClause>),
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}
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2017-03-28 03:53:08 +00:00
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impl OrWhereClause {
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pub fn is_pattern_or_patterns(&self) -> bool {
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match self {
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&OrWhereClause::Clause(WhereClause::Pattern(_)) => true,
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&OrWhereClause::And(ref clauses) => clauses.iter().all(|clause| clause.is_pattern()),
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_ => false,
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}
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}
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}
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2017-03-23 20:10:44 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub struct OrJoin {
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pub unify_vars: UnifyVars,
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pub clauses: Vec<OrWhereClause>,
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}
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2017-01-25 22:06:19 +00:00
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#[allow(dead_code)]
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2017-02-03 02:32:00 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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2017-01-25 22:06:19 +00:00
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pub enum WhereClause {
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Not,
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NotJoin,
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2017-03-23 20:10:44 +00:00
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OrJoin(OrJoin),
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2017-03-16 14:44:56 +00:00
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Pred(Predicate),
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2017-01-25 22:06:19 +00:00
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WhereFn,
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RuleExpr,
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2017-02-03 02:32:00 +00:00
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Pattern(Pattern),
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2017-01-25 22:06:19 +00:00
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}
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#[allow(dead_code)]
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2017-02-03 02:32:00 +00:00
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub struct FindQuery {
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pub find_spec: FindSpec,
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pub default_source: SrcVar,
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pub with: Vec<Variable>,
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pub in_vars: Vec<Variable>,
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pub in_sources: Vec<SrcVar>,
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pub where_clauses: Vec<WhereClause>,
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2017-01-25 22:06:19 +00:00
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// TODO: in_rules;
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}
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2017-03-24 20:09:32 +00:00
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pub trait ContainsVariables {
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fn accumulate_mentioned_variables(&self, acc: &mut BTreeSet<Variable>);
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fn collect_mentioned_variables(&self) -> BTreeSet<Variable> {
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let mut out = BTreeSet::new();
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self.accumulate_mentioned_variables(&mut out);
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out
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}
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}
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impl ContainsVariables for WhereClause {
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fn accumulate_mentioned_variables(&self, acc: &mut BTreeSet<Variable>) {
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use WhereClause::*;
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match self {
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&OrJoin(ref o) => o.accumulate_mentioned_variables(acc),
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&Pred(ref p) => p.accumulate_mentioned_variables(acc),
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&Pattern(ref p) => p.accumulate_mentioned_variables(acc),
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&Not => (),
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&NotJoin => (),
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&WhereFn => (),
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&RuleExpr => (),
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}
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}
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}
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impl ContainsVariables for OrWhereClause {
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fn accumulate_mentioned_variables(&self, acc: &mut BTreeSet<Variable>) {
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use OrWhereClause::*;
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match self {
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&And(ref clauses) => for clause in clauses { clause.accumulate_mentioned_variables(acc) },
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&Clause(ref clause) => clause.accumulate_mentioned_variables(acc),
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}
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}
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}
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impl ContainsVariables for OrJoin {
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fn accumulate_mentioned_variables(&self, acc: &mut BTreeSet<Variable>) {
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for clause in &self.clauses {
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clause.accumulate_mentioned_variables(acc);
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}
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}
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}
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impl ContainsVariables for Predicate {
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fn accumulate_mentioned_variables(&self, acc: &mut BTreeSet<Variable>) {
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for arg in &self.args {
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if let &FnArg::Variable(ref v) = arg {
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acc_ref(acc, v)
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}
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}
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}
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}
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fn acc_ref<T: Clone + Ord>(acc: &mut BTreeSet<T>, v: &T) {
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// Roll on, reference entries!
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if !acc.contains(v) {
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acc.insert(v.clone());
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}
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}
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impl ContainsVariables for Pattern {
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fn accumulate_mentioned_variables(&self, acc: &mut BTreeSet<Variable>) {
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if let PatternNonValuePlace::Variable(ref v) = self.entity {
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acc_ref(acc, v)
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}
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if let PatternNonValuePlace::Variable(ref v) = self.attribute {
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acc_ref(acc, v)
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}
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if let PatternValuePlace::Variable(ref v) = self.value {
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acc_ref(acc, v)
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}
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if let PatternNonValuePlace::Variable(ref v) = self.tx {
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acc_ref(acc, v)
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}
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}
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}
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