Implement parsing of simple :find expressions. (#196) r=nalexander
* Test the mentat_query directory on Travis.
* Export common types from edn.
This allows you to write
use edn::{PlainSymbol,Keyword};
instead of
use edn:🔣:{PlainSymbol,Keyword};
* Add an edn::Value::is_keyword predicate.
* Clean up query, preparing for query-parser.
* Make EDN keywords and symbols take Into<String> arguments.
* Implement parsing of simple :find lists.
* Rustfmt query-parser. Split find and query.
* Review comment: values_to_variables now returns a NotAVariableError on failure.
* Review comment: rename gimme to to_parsed_value.
* Review comment: add comments.
This commit is contained in:
Richard Newman
GitHub
parent
b77d124152
commit
2592506288
16 changed files with 925 additions and 165 deletions
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@ -3,5 +3,6 @@ script:
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- cargo build --verbose
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- cargo test --verbose
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- cargo test --verbose -p edn
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- cargo test --verbose -p mentat_query
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- cargo test --verbose -p mentat_query_parser
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- cargo test --verbose -p mentat_tx_parser
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@ -19,3 +19,6 @@ pub mod types;
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pub mod parse {
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include!(concat!(env!("OUT_DIR"), "/edn.rs"));
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}
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pub use self::types::Value;
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pub use self::symbols::{Keyword, NamespacedKeyword, PlainSymbol, NamespacedSymbol};
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@ -69,10 +69,11 @@ pub struct NamespacedKeyword {
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}
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impl PlainSymbol {
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pub fn new(name: &str) -> Self {
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assert!(!name.is_empty(), "Symbols cannot be unnamed.");
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pub fn new<T>(name: T) -> Self where T: Into<String> {
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let n = name.into();
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assert!(!n.is_empty(), "Symbols cannot be unnamed.");
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return PlainSymbol(name.to_string());
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return PlainSymbol(n);
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}
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}
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@ -86,10 +87,11 @@ impl NamespacedSymbol {
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}
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impl Keyword {
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pub fn new(name: &str) -> Self {
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assert!(!name.is_empty(), "Keywords cannot be unnamed.");
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pub fn new<T>(name: T) -> Self where T: Into<String>{
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let n = name.into();
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assert!(!n.is_empty(), "Keywords cannot be unnamed.");
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return Keyword(name.to_string());
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return Keyword(n);
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}
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}
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@ -41,6 +41,15 @@ pub enum Value {
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use self::Value::*;
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impl Value {
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pub fn is_keyword(&self) -> bool {
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match *self {
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Keyword(_) => true,
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_ => false,
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}
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}
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}
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impl PartialOrd for Value {
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fn partial_cmp(&self, other: &Value) -> Option<Ordering> {
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Some(self.cmp(other))
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@ -3,6 +3,8 @@ name = "mentat_query_parser"
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version = "0.0.1"
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[dependencies]
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combine = "2.1.1"
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[dependencies.edn]
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path = "../edn"
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2
query-parser/README.md
Normal file
2
query-parser/README.md
Normal file
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@ -0,0 +1,2 @@
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See <https://github.com/mozilla/mentat/wiki/Querying> for a description of
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what's going on in this crate, as well as `query` and `query-executor`.
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35
query-parser/src/error.rs
Normal file
35
query-parser/src/error.rs
Normal file
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@ -0,0 +1,35 @@
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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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extern crate combine;
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extern crate edn;
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extern crate mentat_query;
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use self::mentat_query::{FindSpec, FindQuery};
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#[derive(Clone,Debug,Eq,PartialEq)]
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pub struct NotAVariableError(pub edn::Value);
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#[derive(Clone,Debug,Eq,PartialEq)]
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pub enum FindParseError {
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Err,
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}
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#[derive(Clone,Debug,Eq,PartialEq)]
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pub enum QueryParseError {
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InvalidInput(edn::Value),
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EdnParseError(edn::parse::ParseError),
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MissingField(edn::Keyword),
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FindParseError(FindParseError),
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}
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pub type FindParseResult = Result<FindSpec, FindParseError>;
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pub type QueryParseResult = Result<FindQuery, QueryParseError>;
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138
query-parser/src/find.rs
Normal file
138
query-parser/src/find.rs
Normal file
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@ -0,0 +1,138 @@
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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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/// ! This module defines the interface and implementation for parsing an EDN
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/// ! input into a structured Datalog query.
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/// !
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/// ! The query types are defined in the `query` crate, because they
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/// ! are shared between the parser (EDN -> query), the translator
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/// ! (query -> SQL), and the executor (query, SQL -> running code).
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/// !
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/// ! The query input can be in two forms: a 'flat' human-oriented
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/// ! sequence:
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/// !
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/// ! ```clojure
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/// ! [:find ?y :in $ ?x :where [?x :foaf/knows ?y]]
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/// ! ```
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/// !
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/// ! or a more programmatically generable map:
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/// !
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/// ! ```clojure
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/// ! {:find [?y]
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/// ! :in [$]
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/// ! :where [[?x :foaf/knows ?y]]}
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/// ! ```
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/// !
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/// ! We parse by expanding the array format into four parts, treating them as the four
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/// ! parts of the map.
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extern crate edn;
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extern crate mentat_query;
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use std::collections::BTreeMap;
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use self::mentat_query::{FindQuery, SrcVar};
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use super::error::{QueryParseError, QueryParseResult};
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use super::util::{values_to_variables, vec_to_keyword_map};
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#[allow(unused_variables)]
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fn parse_find_parts(find: &[edn::Value],
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ins: Option<&[edn::Value]>,
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with: Option<&[edn::Value]>,
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wheres: &[edn::Value])
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-> QueryParseResult {
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// :find must be an array of plain var symbols (?foo), pull expressions, and aggregates.
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// For now we only support variables and the annotations necessary to declare which
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// flavor of :find we want:
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// ?x ?y ?z = FindRel
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// [?x ...] = FindColl
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// ?x . = FindScalar
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// [?x ?y ?z] = FindTuple
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//
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// :in must be an array of sources ($), rules (%), and vars (?). For now we only support the
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// default source. :in can be omitted, in which case the default is equivalent to `:in $`.
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// TODO: process `ins`.
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let source = SrcVar::DefaultSrc;
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// :with is an array of variables. This is simple, so we don't use a parser.
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let with_vars = with.map(values_to_variables);
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// :wheres is a whole datastructure.
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super::parse::find_seq_to_find_spec(find)
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.map(|spec| {
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FindQuery {
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find_spec: spec,
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default_source: source,
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}
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})
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.map_err(QueryParseError::FindParseError)
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}
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fn parse_find_map(map: BTreeMap<edn::Keyword, Vec<edn::Value>>) -> QueryParseResult {
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// Eagerly awaiting `const fn`.
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let kw_find = edn::Keyword::new("find");
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let kw_in = edn::Keyword::new("in");
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let kw_with = edn::Keyword::new("with");
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let kw_where = edn::Keyword::new("where");
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// Oh, if only we had `guard`.
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if let Some(find) = map.get(&kw_find) {
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if let Some(wheres) = map.get(&kw_where) {
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return parse_find_parts(find,
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map.get(&kw_in).map(|x| x.as_slice()),
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map.get(&kw_with).map(|x| x.as_slice()),
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wheres);
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} else {
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return Err(QueryParseError::MissingField(kw_where));
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}
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} else {
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return Err(QueryParseError::MissingField(kw_find));
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}
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}
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fn parse_find_edn_map(map: BTreeMap<edn::Value, edn::Value>) -> QueryParseResult {
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// Every key must be a Keyword. Every value must be a Vec.
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let mut m = BTreeMap::new();
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if map.is_empty() {
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return parse_find_map(m);
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}
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for (k, v) in map {
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if let edn::Value::Keyword(kw) = k {
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if let edn::Value::Vector(vec) = v {
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m.insert(kw, vec);
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continue;
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} else {
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return Err(QueryParseError::InvalidInput(v));
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}
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} else {
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return Err(QueryParseError::InvalidInput(k));
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}
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}
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parse_find_map(m)
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}
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pub fn parse_find(expr: edn::Value) -> QueryParseResult {
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// No `match` because scoping and use of `expr` in error handling is nuts.
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if let edn::Value::Map(m) = expr {
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return parse_find_edn_map(m);
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}
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if let edn::Value::Vector(ref v) = expr {
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if let Some(m) = vec_to_keyword_map(v) {
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return parse_find_map(m);
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}
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}
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return Err(QueryParseError::InvalidInput(expr));
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}
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@ -8,17 +8,8 @@
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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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// This file is just a stub
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pub fn get_name() -> String {
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return String::from("mentat-query-parser");
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}
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mod error;
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mod util;
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mod parse;
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pub mod find;
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn it_works() {
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assert_eq!(String::from("mentat-query-parser"), get_name());
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}
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}
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265
query-parser/src/parse.rs
Normal file
265
query-parser/src/parse.rs
Normal file
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@ -0,0 +1,265 @@
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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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extern crate combine;
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extern crate edn;
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extern crate mentat_query;
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use self::combine::{eof, many1, parser, satisfy_map, Parser, ParseResult, Stream};
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use self::combine::combinator::{Expected, FnParser, choice, try};
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use self::edn::Value::PlainSymbol;
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use self::mentat_query::{Element, FindSpec, Variable};
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use super::error::{FindParseError, FindParseResult};
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pub struct FindSp<I>(::std::marker::PhantomData<fn(I) -> I>);
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type FindSpParser<O, I> = Expected<FnParser<I, fn(I) -> ParseResult<O, I>>>;
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fn fn_parser<O, I>(f: fn(I) -> ParseResult<O, I>, err: &'static str) -> FindSpParser<O, I>
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where I: Stream<Item = edn::Value>
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{
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parser(f).expected(err)
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}
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/// `satisfy_unwrap!` makes it a little easier to implement a `satisfy_map`
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/// body that matches a particular `Value` enum case, otherwise returning `None`.
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macro_rules! satisfy_unwrap {
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( $cas: path, $var: ident, $body: block ) => {
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satisfy_map(|x: edn::Value| if let $cas($var) = x $body else { None })
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}
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}
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impl<I> FindSp<I>
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where I: Stream<Item = edn::Value>
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{
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fn variable() -> FindSpParser<Variable, I> {
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fn_parser(FindSp::<I>::variable_, "variable")
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}
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fn variable_(input: I) -> ParseResult<Variable, I> {
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satisfy_map(|x: edn::Value| super::util::value_to_variable(&x)).parse_stream(input)
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}
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fn period() -> FindSpParser<(), I> {
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fn_parser(FindSp::<I>::period_, "period")
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}
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fn period_(input: I) -> ParseResult<(), I> {
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satisfy_map(|x: edn::Value| {
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if let PlainSymbol(ref s) = x {
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if s.0.as_str() == "." {
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return Some(());
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}
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}
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return None;
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})
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.parse_stream(input)
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}
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fn ellipsis() -> FindSpParser<(), I> {
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fn_parser(FindSp::<I>::ellipsis_, "ellipsis")
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}
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fn ellipsis_(input: I) -> ParseResult<(), I> {
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satisfy_map(|x: edn::Value| {
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if let PlainSymbol(ref s) = x {
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if s.0.as_str() == "..." {
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return Some(());
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}
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}
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return None;
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})
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.parse_stream(input)
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}
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fn find_scalar() -> FindSpParser<FindSpec, I> {
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fn_parser(FindSp::<I>::find_scalar_, "find_scalar")
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}
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fn find_scalar_(input: I) -> ParseResult<FindSpec, I> {
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(FindSp::variable(), FindSp::period(), eof())
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.map(|(var, _, _)| FindSpec::FindScalar(Element::Variable(var)))
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.parse_stream(input)
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}
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fn find_coll() -> FindSpParser<FindSpec, I> {
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fn_parser(FindSp::<I>::find_coll_, "find_coll")
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}
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fn find_coll_(input: I) -> ParseResult<FindSpec, I> {
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satisfy_unwrap!(edn::Value::Vector, y, {
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let mut p = (FindSp::variable(), FindSp::ellipsis(), eof())
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.map(|(var, _, _)| FindSpec::FindColl(Element::Variable(var)));
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let r: ParseResult<FindSpec, _> = p.parse_lazy(&y[..]).into();
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FindSp::to_parsed_value(r)
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})
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.parse_stream(input)
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}
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fn elements() -> FindSpParser<Vec<Element>, I> {
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fn_parser(FindSp::<I>::elements_, "elements")
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}
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fn elements_(input: I) -> ParseResult<Vec<Element>, I> {
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(many1::<Vec<Variable>, _>(FindSp::variable()), eof())
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.map(|(vars, _)| {
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vars.into_iter()
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.map(Element::Variable)
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.collect()
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})
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.parse_stream(input)
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}
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fn find_rel() -> FindSpParser<FindSpec, I> {
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fn_parser(FindSp::<I>::find_rel_, "find_rel")
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}
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fn find_rel_(input: I) -> ParseResult<FindSpec, I> {
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FindSp::elements().map(FindSpec::FindRel).parse_stream(input)
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}
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|
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fn find_tuple() -> FindSpParser<FindSpec, I> {
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fn_parser(FindSp::<I>::find_tuple_, "find_tuple")
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}
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fn find_tuple_(input: I) -> ParseResult<FindSpec, I> {
|
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satisfy_unwrap!(edn::Value::Vector, y, {
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let r: ParseResult<FindSpec, _> =
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FindSp::elements().map(FindSpec::FindTuple).parse_lazy(&y[..]).into();
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FindSp::to_parsed_value(r)
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})
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.parse_stream(input)
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}
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fn find() -> FindSpParser<FindSpec, I> {
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fn_parser(FindSp::<I>::find_, "find")
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}
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fn find_(input: I) -> ParseResult<FindSpec, I> {
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// Any one of the four specs might apply, so we combine them with `choice`.
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// Our parsers consume input, so we need to wrap them in `try` so that they
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// operate independently.
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choice::<[&mut Parser<Input = I, Output = FindSpec>; 4],
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_>([&mut try(FindSp::find_scalar()),
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&mut try(FindSp::find_coll()),
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&mut try(FindSp::find_tuple()),
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&mut try(FindSp::find_rel())])
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.parse_stream(input)
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}
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fn to_parsed_value<T>(r: ParseResult<T, I>) -> Option<T> {
|
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r.ok().map(|x| x.0)
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}
|
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}
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macro_rules! assert_parses_to {
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( $parser: path, $input: expr, $expected: expr ) => {{
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let mut par = $parser();
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let result = par.parse(&$input[..]);
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assert_eq!(result, Ok(($expected, &[][..])));
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}}
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}
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#[test]
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||||
fn test_find_sp_variable() {
|
||||
let sym = edn::PlainSymbol::new("?x");
|
||||
let input = [edn::Value::PlainSymbol(sym.clone())];
|
||||
assert_parses_to!(FindSp::variable, input, Variable(sym));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_find_scalar() {
|
||||
let sym = edn::PlainSymbol::new("?x");
|
||||
let period = edn::PlainSymbol::new(".");
|
||||
let input = [edn::Value::PlainSymbol(sym.clone()), edn::Value::PlainSymbol(period.clone())];
|
||||
assert_parses_to!(FindSp::find_scalar,
|
||||
input,
|
||||
FindSpec::FindScalar(Element::Variable(Variable(sym))));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_find_coll() {
|
||||
let sym = edn::PlainSymbol::new("?x");
|
||||
let period = edn::PlainSymbol::new("...");
|
||||
let input = [edn::Value::Vector(vec![edn::Value::PlainSymbol(sym.clone()),
|
||||
edn::Value::PlainSymbol(period.clone())])];
|
||||
assert_parses_to!(FindSp::find_coll,
|
||||
input,
|
||||
FindSpec::FindColl(Element::Variable(Variable(sym))));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_find_rel() {
|
||||
let vx = edn::PlainSymbol::new("?x");
|
||||
let vy = edn::PlainSymbol::new("?y");
|
||||
let input = [edn::Value::PlainSymbol(vx.clone()), edn::Value::PlainSymbol(vy.clone())];
|
||||
assert_parses_to!(FindSp::find_rel,
|
||||
input,
|
||||
FindSpec::FindRel(vec![Element::Variable(Variable(vx)),
|
||||
Element::Variable(Variable(vy))]));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_find_tuple() {
|
||||
let vx = edn::PlainSymbol::new("?x");
|
||||
let vy = edn::PlainSymbol::new("?y");
|
||||
let input = [edn::Value::Vector(vec![edn::Value::PlainSymbol(vx.clone()),
|
||||
edn::Value::PlainSymbol(vy.clone())])];
|
||||
assert_parses_to!(FindSp::find_tuple,
|
||||
input,
|
||||
FindSpec::FindTuple(vec![Element::Variable(Variable(vx)),
|
||||
Element::Variable(Variable(vy))]));
|
||||
}
|
||||
|
||||
// Parse a sequence of values into one of four find specs.
|
||||
//
|
||||
// `:find` must be an array of plain var symbols (?foo), pull expressions, and aggregates.
|
||||
// For now we only support variables and the annotations necessary to declare which
|
||||
// flavor of :find we want:
|
||||
//
|
||||
//
|
||||
// `?x ?y ?z ` = FindRel
|
||||
// `[?x ...] ` = FindColl
|
||||
// `?x . ` = FindScalar
|
||||
// `[?x ?y ?z]` = FindTuple
|
||||
//
|
||||
pub fn find_seq_to_find_spec(find: &[edn::Value]) -> FindParseResult {
|
||||
FindSp::find()
|
||||
.parse(find)
|
||||
.map(|x| x.0)
|
||||
.map_err(|_| FindParseError::Err)
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_find_processing() {
|
||||
let vx = edn::PlainSymbol::new("?x");
|
||||
let vy = edn::PlainSymbol::new("?y");
|
||||
let ellipsis = edn::PlainSymbol::new("...");
|
||||
let period = edn::PlainSymbol::new(".");
|
||||
|
||||
let scalar = [edn::Value::PlainSymbol(vx.clone()), edn::Value::PlainSymbol(period.clone())];
|
||||
let tuple = [edn::Value::Vector(vec![edn::Value::PlainSymbol(vx.clone()),
|
||||
edn::Value::PlainSymbol(vy.clone())])];
|
||||
let coll = [edn::Value::Vector(vec![edn::Value::PlainSymbol(vx.clone()),
|
||||
edn::Value::PlainSymbol(ellipsis.clone())])];
|
||||
let rel = [edn::Value::PlainSymbol(vx.clone()), edn::Value::PlainSymbol(vy.clone())];
|
||||
|
||||
assert_eq!(Ok(FindSpec::FindScalar(Element::Variable(Variable(vx.clone())))),
|
||||
find_seq_to_find_spec(&scalar));
|
||||
assert_eq!(Ok(FindSpec::FindTuple(vec![Element::Variable(Variable(vx.clone())),
|
||||
Element::Variable(Variable(vy.clone()))])),
|
||||
find_seq_to_find_spec(&tuple));
|
||||
assert_eq!(Ok(FindSpec::FindColl(Element::Variable(Variable(vx.clone())))),
|
||||
find_seq_to_find_spec(&coll));
|
||||
assert_eq!(Ok(FindSpec::FindRel(vec![Element::Variable(Variable(vx.clone())),
|
||||
Element::Variable(Variable(vy.clone()))])),
|
||||
find_seq_to_find_spec(&rel));
|
||||
}
|
||||
187
query-parser/src/util.rs
Normal file
187
query-parser/src/util.rs
Normal file
|
|
@ -0,0 +1,187 @@
|
|||
// Copyright 2016 Mozilla
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
|
||||
// this file except in compliance with the License. You may obtain a copy of the
|
||||
// License at http://www.apache.org/licenses/LICENSE-2.0
|
||||
// Unless required by applicable law or agreed to in writing, software distributed
|
||||
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
|
||||
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
|
||||
// specific language governing permissions and limitations under the License.
|
||||
|
||||
extern crate edn;
|
||||
extern crate mentat_query;
|
||||
|
||||
use std::collections::BTreeMap;
|
||||
|
||||
use self::edn::Value::PlainSymbol;
|
||||
use self::mentat_query::Variable;
|
||||
use super::error::NotAVariableError;
|
||||
|
||||
/// If the provided EDN value is a PlainSymbol beginning with '?', return
|
||||
/// it wrapped in a Variable. If not, return None.
|
||||
pub fn value_to_variable(v: &edn::Value) -> Option<Variable> {
|
||||
if let PlainSymbol(ref sym) = *v {
|
||||
if sym.0.starts_with('?') {
|
||||
return Some(Variable(sym.clone()));
|
||||
}
|
||||
}
|
||||
return None;
|
||||
}
|
||||
|
||||
/// If the provided slice of EDN values are all variables as
|
||||
/// defined by `value_to_variable`, return a Vec of Variables.
|
||||
/// Otherwise, return the unrecognized Value.
|
||||
pub fn values_to_variables(vals: &[edn::Value]) -> Result<Vec<Variable>, NotAVariableError> {
|
||||
let mut out: Vec<Variable> = Vec::with_capacity(vals.len());
|
||||
for v in vals {
|
||||
if let Some(var) = value_to_variable(v) {
|
||||
out.push(var);
|
||||
continue;
|
||||
}
|
||||
return Err(NotAVariableError(v.clone()));
|
||||
}
|
||||
return Ok(out);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_values_to_variables() {
|
||||
// TODO
|
||||
}
|
||||
|
||||
/// Take a slice of EDN values, as would be extracted from an
|
||||
/// `edn::Value::Vector`, and turn it into a map.
|
||||
///
|
||||
/// The slice must consist of subsequences of an initial plain
|
||||
/// keyword, followed by one or more non-plain-keyword values.
|
||||
///
|
||||
/// The plain keywords are used as keys into the resulting map.
|
||||
/// The values are accumulated into vectors.
|
||||
///
|
||||
/// Invalid input causes this function to return `None`.
|
||||
///
|
||||
/// TODO: this function can be generalized to take an arbitrary
|
||||
/// destructuring/break function, yielding a map with a custom
|
||||
/// key type and splitting in the right places.
|
||||
pub fn vec_to_keyword_map(vec: &[edn::Value]) -> Option<BTreeMap<edn::Keyword, Vec<edn::Value>>> {
|
||||
let mut m = BTreeMap::new();
|
||||
|
||||
if vec.is_empty() {
|
||||
return Some(m);
|
||||
}
|
||||
|
||||
if vec.len() == 1 {
|
||||
return None;
|
||||
}
|
||||
|
||||
// Turn something like
|
||||
//
|
||||
// `[:foo 1 2 3 :bar 4 5 6]`
|
||||
//
|
||||
// into
|
||||
//
|
||||
// `Some((:foo, [1 2 3]))`
|
||||
fn step(slice: &[edn::Value]) -> Option<(edn::Keyword, Vec<edn::Value>)> {
|
||||
// [:foo 1 2 3 :bar] is invalid: nothing follows `:bar`.
|
||||
if slice.len() < 2 {
|
||||
return None;
|
||||
}
|
||||
|
||||
// The first item must be a keyword.
|
||||
if let edn::Value::Keyword(ref k) = slice[0] {
|
||||
|
||||
// The second can't be: [:foo :bar 1 2 3] is invalid.
|
||||
if slice[1].is_keyword() {
|
||||
return None;
|
||||
}
|
||||
|
||||
// Accumulate items until we reach the next keyword.
|
||||
let mut acc = Vec::new();
|
||||
for v in &slice[1..] {
|
||||
if v.is_keyword() {
|
||||
break;
|
||||
}
|
||||
acc.push(v.clone());
|
||||
}
|
||||
return Some((k.clone(), acc));
|
||||
}
|
||||
|
||||
None
|
||||
}
|
||||
|
||||
let mut bits = vec;
|
||||
while !bits.is_empty() {
|
||||
match step(bits) {
|
||||
Some((k, v)) => {
|
||||
bits = &bits[(v.len() + 1)..];
|
||||
|
||||
// Duplicate keys aren't allowed.
|
||||
if m.contains_key(&k) {
|
||||
return None;
|
||||
}
|
||||
m.insert(k, v);
|
||||
},
|
||||
None => return None,
|
||||
}
|
||||
}
|
||||
return Some(m);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_vec_to_keyword_map() {
|
||||
let foo = edn::symbols::Keyword("foo".to_string());
|
||||
let bar = edn::symbols::Keyword("bar".to_string());
|
||||
let baz = edn::symbols::Keyword("baz".to_string());
|
||||
|
||||
// [:foo 1 2 3 :bar 4]
|
||||
let input = vec!(edn::Value::Keyword(foo.clone()),
|
||||
edn::Value::Integer(1),
|
||||
edn::Value::Integer(2),
|
||||
edn::Value::Integer(3),
|
||||
edn::Value::Keyword(bar.clone()),
|
||||
edn::Value::Integer(4));
|
||||
|
||||
let m = vec_to_keyword_map(&input).unwrap();
|
||||
|
||||
assert!(m.contains_key(&foo));
|
||||
assert!(m.contains_key(&bar));
|
||||
assert!(!m.contains_key(&baz));
|
||||
|
||||
let onetwothree = vec!(edn::Value::Integer(1),
|
||||
edn::Value::Integer(2),
|
||||
edn::Value::Integer(3));
|
||||
let four = vec!(edn::Value::Integer(4));
|
||||
|
||||
assert_eq!(m.get(&foo).unwrap(), &onetwothree);
|
||||
assert_eq!(m.get(&bar).unwrap(), &four);
|
||||
|
||||
// Trailing keywords aren't allowed.
|
||||
assert_eq!(None,
|
||||
vec_to_keyword_map(&vec!(edn::Value::Keyword(foo.clone()))));
|
||||
assert_eq!(None,
|
||||
vec_to_keyword_map(&vec!(edn::Value::Keyword(foo.clone()),
|
||||
edn::Value::Integer(2),
|
||||
edn::Value::Keyword(bar.clone()))));
|
||||
|
||||
// Duplicate keywords aren't allowed.
|
||||
assert_eq!(None,
|
||||
vec_to_keyword_map(&vec!(edn::Value::Keyword(foo.clone()),
|
||||
edn::Value::Integer(2),
|
||||
edn::Value::Keyword(foo.clone()),
|
||||
edn::Value::Integer(1))));
|
||||
|
||||
// Starting with anything but a keyword isn't allowed.
|
||||
assert_eq!(None,
|
||||
vec_to_keyword_map(&vec!(edn::Value::Integer(2),
|
||||
edn::Value::Keyword(foo.clone()),
|
||||
edn::Value::Integer(1))));
|
||||
|
||||
// Consecutive keywords aren't allowed.
|
||||
assert_eq!(None,
|
||||
vec_to_keyword_map(&vec!(edn::Value::Keyword(foo.clone()),
|
||||
edn::Value::Keyword(bar.clone()),
|
||||
edn::Value::Integer(1))));
|
||||
|
||||
// Empty lists return an empty map.
|
||||
assert_eq!(BTreeMap::new(), vec_to_keyword_map(&vec!()).unwrap());
|
||||
}
|
||||
|
||||
35
query-parser/tests/find_tests.rs
Normal file
35
query-parser/tests/find_tests.rs
Normal file
|
|
@ -0,0 +1,35 @@
|
|||
// Copyright 2016 Mozilla
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
|
||||
// this file except in compliance with the License. You may obtain a copy of the
|
||||
// License at http://www.apache.org/licenses/LICENSE-2.0
|
||||
// Unless required by applicable law or agreed to in writing, software distributed
|
||||
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
|
||||
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
|
||||
// specific language governing permissions and limitations under the License.
|
||||
|
||||
extern crate mentat_query_parser;
|
||||
extern crate mentat_query;
|
||||
extern crate edn;
|
||||
|
||||
use mentat_query::FindSpec::*;
|
||||
use mentat_query::Element;
|
||||
use mentat_query::Variable;
|
||||
use edn::PlainSymbol;
|
||||
|
||||
///! N.B., parsing a query can be done without reference to a DB.
|
||||
///! Processing the parsed query into something we can work with
|
||||
///! for planning involves interrogating the schema and idents in
|
||||
///! the store.
|
||||
///! See <https://github.com/mozilla/mentat/wiki/Querying> for more.
|
||||
|
||||
#[test]
|
||||
fn can_parse_trivial_find() {
|
||||
let find = FindScalar(Element::Variable(Variable(PlainSymbol("?foo".to_string()))));
|
||||
|
||||
if let FindScalar(Element::Variable(Variable(PlainSymbol(name)))) = find {
|
||||
assert_eq!("?foo", name);
|
||||
} else {
|
||||
panic!()
|
||||
}
|
||||
}
|
||||
|
|
@ -3,5 +3,8 @@ name = "mentat_query"
|
|||
version = "0.0.1"
|
||||
|
||||
[dependencies]
|
||||
[dependencies.num] # For EDN value usage.
|
||||
[dependencies.ordered-float]
|
||||
|
||||
[dependencies.edn]
|
||||
path = "../edn"
|
||||
|
|
|
|||
|
|
@ -1,135 +0,0 @@
|
|||
// Copyright 2016 Mozilla
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
|
||||
// this file except in compliance with the License. You may obtain a copy of the
|
||||
// License at http://www.apache.org/licenses/LICENSE-2.0
|
||||
// Unless required by applicable law or agreed to in writing, software distributed
|
||||
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
|
||||
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
|
||||
// specific language governing permissions and limitations under the License.
|
||||
|
||||
///! This module defines some core types that support find expressions: sources,
|
||||
///! variables, expressions, etc.
|
||||
///! These are produced as 'fuel' by the query parser, consumed by the query
|
||||
///! translator and executor.
|
||||
///!
|
||||
///! Many of these types are defined as simple structs that are little more than
|
||||
///! a richer type alias: a variable, for example, is really just a fancy kind
|
||||
///! of string.
|
||||
///!
|
||||
///! At some point in the future, we might consider reducing copying and memory
|
||||
///! usage by recasting all of these string-holding structs and enums in terms
|
||||
///! of string references, with those references being slices of some parsed
|
||||
///! input query string, and valid for the lifetime of that string.
|
||||
///!
|
||||
///! For now, for the sake of simplicity, all of these strings are heap-allocated.
|
||||
///!
|
||||
///! Furthermore, we might cut out some of the chaff here: each time a 'tagged'
|
||||
///! type is used within an enum, we have an opportunity to simplify and use the
|
||||
///! inner type directly in conjunction with matching on the enum. Before diving
|
||||
///! deeply into this it's worth recognizing that this loss of 'sovereignty' is
|
||||
///! a tradeoff against well-typed function signatures and other such boundaries.
|
||||
|
||||
|
||||
// TODO: support other kinds of sources.
|
||||
#[derive(Clone,Debug,Eq,PartialEq)]
|
||||
pub enum SrcVar {
|
||||
DefaultSrc,
|
||||
}
|
||||
|
||||
pub enum Constant {} // This is essentially Box. TODO: flesh out.
|
||||
|
||||
#[derive(Clone,Debug,Eq,PartialEq)]
|
||||
pub struct Variable {
|
||||
pub name: String,
|
||||
}
|
||||
|
||||
pub enum FnArg {
|
||||
Constant { constant: Constant },
|
||||
Variable { variable: Variable },
|
||||
Src { src: SrcVar },
|
||||
}
|
||||
|
||||
pub enum PullPattern {
|
||||
Constant { constant: Constant },
|
||||
Variable { variable: Variable },
|
||||
}
|
||||
|
||||
pub struct Pull {
|
||||
pub src: SrcVar,
|
||||
pub var: Variable,
|
||||
pub pattern: PullPattern, // Constant, variable, or plain variable.
|
||||
}
|
||||
|
||||
pub struct Aggregate {
|
||||
pub fn_name: String,
|
||||
pub args: Vec<FnArg>,
|
||||
}
|
||||
|
||||
// TODO: look up the idiomatic way to express these kinds of type
|
||||
// combinations in Rust. It must be common in ASTs. Trait objects
|
||||
// presumably aren't the answer…
|
||||
pub enum Element {
|
||||
Variable { variable: Variable },
|
||||
Pull { expression: Pull },
|
||||
Aggregate { expression: Aggregate },
|
||||
}
|
||||
|
||||
/// A definition of the first part of a find query: the
|
||||
/// `[:find ?foo ?bar…]` bit.
|
||||
///
|
||||
/// There are four different kinds of find specs, allowing you to query for
|
||||
/// a single value, a collection of values from different entities, a single
|
||||
/// tuple (relation), or a collection of tuples.
|
||||
///
|
||||
/// Examples:
|
||||
///
|
||||
/// ```rust
|
||||
/// # use mentat_query::find::{FindSpec, Element, Variable};
|
||||
///
|
||||
/// // TODO: this feels clunky.
|
||||
/// let foo = Variable { name: "foo".to_string() };
|
||||
/// let bar = Variable { name: "bar".to_string() };
|
||||
/// let elements = vec![
|
||||
/// Element::Variable { variable: foo },
|
||||
/// Element::Variable { variable: bar },
|
||||
/// ];
|
||||
/// let rel = FindSpec::FindRel { elements: elements };
|
||||
///
|
||||
/// if let FindSpec::FindRel { elements } = rel {
|
||||
/// assert_eq!(2, elements.len());
|
||||
/// }
|
||||
/// ```
|
||||
///
|
||||
pub enum FindSpec {
|
||||
/// Returns an array of arrays.
|
||||
FindRel { elements: Vec<Element> },
|
||||
|
||||
/// Returns an array of scalars, usually homogeneous.
|
||||
/// This is equivalent to mapping over the results of a `FindRel`,
|
||||
/// returning the first value of each.
|
||||
FindColl { element: Element },
|
||||
|
||||
/// Returns a single tuple: a heterogeneous array of scalars. Equivalent to
|
||||
/// taking the first result from a `FindRel`.
|
||||
FindTuple { elements: Vec<Element> },
|
||||
|
||||
/// Returns a single scalar value. Equivalent to taking the first result
|
||||
/// from a `FindColl`.
|
||||
FindScalar { element: Element },
|
||||
}
|
||||
|
||||
/// Returns true if the provided `FindSpec` returns at most one result.
|
||||
pub fn is_unit_limited(spec: &FindSpec) -> bool {
|
||||
match spec {
|
||||
&FindSpec::FindScalar { .. } => true,
|
||||
&FindSpec::FindTuple { .. } => true,
|
||||
&FindSpec::FindRel { .. } => false,
|
||||
&FindSpec::FindColl { .. } => false,
|
||||
}
|
||||
}
|
||||
|
||||
/// Returns true if the provided `FindSpec` cares about distinct results.
|
||||
pub fn requires_distinct(spec: &FindSpec) -> bool {
|
||||
return !is_unit_limited(spec);
|
||||
}
|
||||
234
query/src/lib.rs
234
query/src/lib.rs
|
|
@ -8,4 +8,236 @@
|
|||
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
|
||||
// specific language governing permissions and limitations under the License.
|
||||
|
||||
pub mod find;
|
||||
///! This module defines some core types that support find expressions: sources,
|
||||
///! variables, expressions, etc.
|
||||
///! These are produced as 'fuel' by the query parser, consumed by the query
|
||||
///! translator and executor.
|
||||
///!
|
||||
///! Many of these types are defined as simple structs that are little more than
|
||||
///! a richer type alias: a variable, for example, is really just a fancy kind
|
||||
///! of string.
|
||||
///!
|
||||
///! At some point in the future, we might consider reducing copying and memory
|
||||
///! usage by recasting all of these string-holding structs and enums in terms
|
||||
///! of string references, with those references being slices of some parsed
|
||||
///! input query string, and valid for the lifetime of that string.
|
||||
///!
|
||||
///! For now, for the sake of simplicity, all of these strings are heap-allocated.
|
||||
///!
|
||||
///! Furthermore, we might cut out some of the chaff here: each time a 'tagged'
|
||||
///! type is used within an enum, we have an opportunity to simplify and use the
|
||||
///! inner type directly in conjunction with matching on the enum. Before diving
|
||||
///! deeply into this it's worth recognizing that this loss of 'sovereignty' is
|
||||
///! a tradeoff against well-typed function signatures and other such boundaries.
|
||||
|
||||
extern crate edn;
|
||||
extern crate num;
|
||||
extern crate ordered_float;
|
||||
|
||||
use num::BigInt;
|
||||
use ordered_float::OrderedFloat;
|
||||
use edn::{NamespacedKeyword, PlainSymbol};
|
||||
|
||||
pub type SrcVarName = String; // Do not include the required syntactic '$'.
|
||||
|
||||
#[derive(Clone, Debug, PartialEq, Eq)]
|
||||
pub struct Variable(pub PlainSymbol);
|
||||
|
||||
#[derive(Clone,Debug,Eq,PartialEq)]
|
||||
pub enum SrcVar {
|
||||
DefaultSrc,
|
||||
NamedSrc(SrcVarName),
|
||||
}
|
||||
|
||||
/// These are the scalar values representable in EDN.
|
||||
#[derive(Clone,Debug,Eq,PartialEq)]
|
||||
pub enum NonIntegerConstant {
|
||||
Boolean(bool),
|
||||
BigInteger(BigInt),
|
||||
Float(OrderedFloat<f64>),
|
||||
Text(String),
|
||||
}
|
||||
|
||||
pub enum FnArg {
|
||||
Variable(Variable),
|
||||
SrcVar(SrcVar),
|
||||
EntidOrInteger(i64),
|
||||
Ident(NamespacedKeyword),
|
||||
Constant(NonIntegerConstant),
|
||||
}
|
||||
|
||||
/// e, a, tx can't be values -- no strings, no floats -- and so
|
||||
/// they can only be variables, entity IDs, ident keywords, or
|
||||
/// placeholders.
|
||||
/// This encoding allows us to represent integers that aren't
|
||||
/// entity IDs. That'll get filtered out in the context of the
|
||||
/// database.
|
||||
pub enum PatternNonValuePlace {
|
||||
Placeholder,
|
||||
Variable(Variable),
|
||||
Entid(u64), // Note unsigned. See #190.
|
||||
Ident(NamespacedKeyword),
|
||||
}
|
||||
|
||||
/// The `v` part of a pattern can be much broader: it can represent
|
||||
/// integers that aren't entity IDs (particularly negative integers),
|
||||
/// strings, and all the rest. We group those under `Constant`.
|
||||
pub enum PatternValuePlace {
|
||||
Placeholder,
|
||||
Variable(Variable),
|
||||
EntidOrInteger(i64),
|
||||
Ident(NamespacedKeyword),
|
||||
Constant(NonIntegerConstant),
|
||||
}
|
||||
|
||||
/*
|
||||
pub enum PullPattern {
|
||||
Constant(Constant),
|
||||
Variable(Variable),
|
||||
}
|
||||
|
||||
pub struct Pull {
|
||||
pub src: SrcVar,
|
||||
pub var: Variable,
|
||||
pub pattern: PullPattern, // Constant, variable, or plain variable.
|
||||
}
|
||||
*/
|
||||
|
||||
/*
|
||||
pub struct Aggregate {
|
||||
pub fn_name: String,
|
||||
pub args: Vec<FnArg>,
|
||||
}
|
||||
*/
|
||||
|
||||
#[derive(Clone,Debug,Eq,PartialEq)]
|
||||
pub enum Element {
|
||||
Variable(Variable),
|
||||
// Aggregate(Aggregate), // TODO
|
||||
// Pull(Pull), // TODO
|
||||
}
|
||||
|
||||
/// A definition of the first part of a find query: the
|
||||
/// `[:find ?foo ?bar…]` bit.
|
||||
///
|
||||
/// There are four different kinds of find specs, allowing you to query for
|
||||
/// a single value, a collection of values from different entities, a single
|
||||
/// tuple (relation), or a collection of tuples.
|
||||
///
|
||||
/// Examples:
|
||||
///
|
||||
/// ```rust
|
||||
/// # extern crate edn;
|
||||
/// # extern crate mentat_query;
|
||||
/// # use edn::PlainSymbol;
|
||||
/// # use mentat_query::{Element, FindSpec, Variable};
|
||||
///
|
||||
/// # fn main() {
|
||||
///
|
||||
/// let elements = vec![
|
||||
/// Element::Variable(Variable(PlainSymbol("?foo".to_string()))),
|
||||
/// Element::Variable(Variable(PlainSymbol("?bar".to_string()))),
|
||||
/// ];
|
||||
/// let rel = FindSpec::FindRel(elements);
|
||||
///
|
||||
/// if let FindSpec::FindRel(elements) = rel {
|
||||
/// assert_eq!(2, elements.len());
|
||||
/// }
|
||||
///
|
||||
/// # }
|
||||
/// ```
|
||||
///
|
||||
#[derive(Clone,Debug,Eq,PartialEq)]
|
||||
pub enum FindSpec {
|
||||
/// Returns an array of arrays.
|
||||
FindRel(Vec<Element>),
|
||||
|
||||
/// Returns an array of scalars, usually homogeneous.
|
||||
/// This is equivalent to mapping over the results of a `FindRel`,
|
||||
/// returning the first value of each.
|
||||
FindColl(Element),
|
||||
|
||||
/// Returns a single tuple: a heterogeneous array of scalars. Equivalent to
|
||||
/// taking the first result from a `FindRel`.
|
||||
FindTuple(Vec<Element>),
|
||||
|
||||
/// Returns a single scalar value. Equivalent to taking the first result
|
||||
/// from a `FindColl`.
|
||||
FindScalar(Element),
|
||||
}
|
||||
|
||||
#[derive(Clone,Debug,Eq,PartialEq)]
|
||||
#[allow(dead_code)]
|
||||
pub struct FindQuery {
|
||||
pub find_spec: FindSpec,
|
||||
pub default_source: SrcVar,
|
||||
}
|
||||
|
||||
/// Returns true if the provided `FindSpec` returns at most one result.
|
||||
pub fn is_unit_limited(spec: &FindSpec) -> bool {
|
||||
match spec {
|
||||
&FindSpec::FindScalar(..) => true,
|
||||
&FindSpec::FindTuple(..) => true,
|
||||
&FindSpec::FindRel(..) => false,
|
||||
&FindSpec::FindColl(..) => false,
|
||||
}
|
||||
}
|
||||
|
||||
/// Returns true if the provided `FindSpec` cares about distinct results.
|
||||
///
|
||||
/// I use the words "cares about" because find is generally defined in terms of producing distinct
|
||||
/// results at the Datalog level.
|
||||
///
|
||||
/// Two of the find specs (scalar and tuple) produce only a single result. Those don't need to be
|
||||
/// run with `SELECT DISTINCT`, because we're only consuming a single result. Those queries will be
|
||||
/// run with `LIMIT 1`.
|
||||
///
|
||||
/// Additionally, some projections cannot produce duplicate results: `[:find (max ?x) …]`, for
|
||||
/// example.
|
||||
///
|
||||
/// This function gives us the hook to add that logic when we're ready.
|
||||
///
|
||||
/// Beyond this, `DISTINCT` is not always needed. For example, in some kinds of accumulation or
|
||||
/// sampling projections we might not need to do it at the SQL level because we're consuming into
|
||||
/// a dupe-eliminating data structure like a Set, or we know that a particular query cannot produce
|
||||
/// duplicate results.
|
||||
pub fn requires_distinct(spec: &FindSpec) -> bool {
|
||||
return !is_unit_limited(spec);
|
||||
}
|
||||
|
||||
// Note that the "implicit blank" rule applies.
|
||||
// A pattern with a reversed attribute — :foo/_bar — is reversed
|
||||
// at the point of parsing. These `Pattern` instances only represent
|
||||
// one direction.
|
||||
#[allow(dead_code)]
|
||||
pub struct Pattern {
|
||||
source: Option<SrcVar>,
|
||||
entity: PatternNonValuePlace,
|
||||
attribute: PatternNonValuePlace,
|
||||
value: PatternValuePlace,
|
||||
tx: PatternNonValuePlace,
|
||||
}
|
||||
|
||||
#[allow(dead_code)]
|
||||
pub enum WhereClause {
|
||||
/*
|
||||
Not,
|
||||
NotJoin,
|
||||
Or,
|
||||
OrJoin,
|
||||
Pred,
|
||||
WhereFn,
|
||||
RuleExpr,
|
||||
*/
|
||||
Pattern,
|
||||
}
|
||||
|
||||
#[allow(dead_code)]
|
||||
pub struct Query {
|
||||
find: FindSpec,
|
||||
with: Vec<Variable>,
|
||||
in_vars: Vec<Variable>,
|
||||
in_sources: Vec<SrcVar>,
|
||||
where_clauses: Vec<WhereClause>,
|
||||
// TODO: in_rules;
|
||||
}
|
||||
|
|
|
|||
10
src/lib.rs
10
src/lib.rs
|
|
@ -21,11 +21,6 @@ pub fn get_name() -> String {
|
|||
return String::from("mentat");
|
||||
}
|
||||
|
||||
// Just an example of using a dependency
|
||||
pub fn get_parser_name() -> String {
|
||||
return mentat_query_parser::get_name();
|
||||
}
|
||||
|
||||
// Will ultimately not return the sqlite connection directly
|
||||
pub fn get_connection() -> Connection {
|
||||
return Connection::open_in_memory().unwrap();
|
||||
|
|
@ -40,9 +35,4 @@ mod tests {
|
|||
fn can_import_edn() {
|
||||
assert_eq!("foo", Keyword::new("foo").0);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn can_import_parser() {
|
||||
assert_eq!(String::from("mentat-query-parser"), get_parser_name());
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in a new issue