Introduce apollo-compiler crate: beginnings of a incremental, query-based compiler for graphql (#202)

Beginnings of apollo-compiler crate, an incremental, query-based compiler built on top of `salsa-rs`.

This PR uses salsa's queries to create a memoised database of Executable Definitions, Fragments and Operations.
Based on the context built while populating the database we will then be able to run any possible validations to produce diagnostics. This PR does variable validation in operation definitions, operation definition name validations as well as subscription field validations.

Author: lrlna

Cargo.toml

@@ -1,2 +1,9 @@
 [workspace]
-members = ["xtask/", "crates/apollo-encoder", "crates/apollo-parser", "crates/apollo-smith", "fuzz"]
+members = [
+    "xtask/",
+    "crates/apollo-encoder",
+    "crates/apollo-parser",
+    "crates/apollo-compiler",
+    "crates/apollo-smith",
+    "fuzz",
+]

crates/apollo-compiler/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "apollo-compiler"
+version = "0.1.0"
+authors = ["Irina Shestak <[email protected]>"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/apollographql/apollo-rs"
+documentation = "https://docs.rs/apollo-conmpiler"
+description = "Semantic analyzer for apollo-parser's AST."
+keywords = ["graphql", "parser", "graphql-tooling", "apollographql"]
+categories = [
+    "compilers",
+    "development-tools",
+    "parser-implementations",
+    "parsing",
+    "web-programming",
+]
+edition = "2021"
+
+[dependencies]
+apollo-parser = { path = "../apollo-parser" }
+salsa = "0.16.1"
+uuid = { version = "0.8.2", features = ["serde", "v4"] }
+ordered-float = { version = "2.10.0", features = ["std"] }
+
+[dev-dependencies]
+expect-test = "1.1"

crates/apollo-compiler/LICENSE-APACHE

@@ -0,0 +1 @@
+../../LICENSE-APACHE

crates/apollo-compiler/LICENSE-MIT

@@ -0,0 +1 @@
+../../LICENSE-MIT

crates/apollo-compiler/examples/hello_world.rs

@@ -0,0 +1,36 @@
+use std::{fs, path::Path};
+
+use apollo_compiler::{values, ApolloCompiler};
+
+fn compile_query() -> Option<values::FragmentDefinition> {
+    let file = Path::new("crates/apollo-compiler/examples/query_with_errors.graphql");
+    let src = fs::read_to_string(file).expect("Could not read schema file.");
+
+    let ctx = ApolloCompiler::new(&src);
+    // let errors = ctx.validate();
+
+    let operations = ctx.operations();
+    let operation_names: Vec<_> = operations.iter().filter_map(|op| op.name()).collect();
+    assert_eq!(["ExampleQuery"], operation_names.as_slice());
+    let frags = ctx.fragments();
+    let fragments: Vec<_> = frags.iter().map(|frag| frag.name()).collect();
+    assert_eq!(["vipCustomer"], fragments.as_slice());
+
+    let operation_variables: Vec<String> = ctx
+        .operations()
+        .find("ExampleQuery")?
+        .variables()
+        .iter()
+        .map(|var| var.name())
+        .collect();
+
+    assert_eq!(["definedVariable"], operation_variables.as_slice());
+    ctx.fragments().find("vipCustomer")
+}
+
+fn main() -> Result<(), ()> {
+    match compile_query() {
+        Some(_fragment) => Ok(()),
+        None => Err(()),
+    }
+}

crates/apollo-compiler/examples/query_with_errors.graphql

@@ -0,0 +1,12 @@
+query ExampleQuery($definedVariable: String) {
+  topProducts(first: $undefinedVariable) {
+    name
+  }
+}
+
+fragment vipCustomer on User {
+  id
+  name
+  profilePic(size: 50)
+  status
+}

crates/apollo-compiler/src/diagnostics.rs

@@ -0,0 +1,42 @@
+// NOTE @lrlna: only syntax errors currently have the source data.
+//
+// TODO: figure out a nice way of going back to the AST and get its source data
+// given a current Value, which will make sure the rest of the diagnostics have
+// source data.
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum ApolloDiagnostic {
+    Error(ErrorDiagnostic),
+    Warning(WarningDiagnostic),
+    Hint(HintDiagnostic),
+    Suggestion(SuggestionDiagnostic),
+}
+
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum ErrorDiagnostic {
+    MissingIdent(String),
+    SingleRootField(String),
+    UniqueOperationDefinition {
+        message: String,
+        operation: String,
+    },
+    UndefinedVariable {
+        message: String,
+        variable: String,
+    },
+    SyntaxError {
+        message: String,
+        data: String,
+        index: usize,
+    },
+}
+
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum WarningDiagnostic {
+    UnusedVariable { message: String, variable: String },
+}
+
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum HintDiagnostic {}
+
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum SuggestionDiagnostic {}

crates/apollo-compiler/src/lib.rs

@@ -0,0 +1,102 @@
+mod diagnostics;
+mod queries;
+#[cfg(test)]
+mod tests;
+mod validation;
+
+use std::sync::Arc;
+
+use apollo_parser::{ast, SyntaxTree};
+pub use queries::{
+    database::{Database, SourceDatabase},
+    values,
+};
+
+use diagnostics::ApolloDiagnostic;
+use validation::Validator;
+
+pub struct ApolloCompiler {
+    db: Database,
+}
+
+impl ApolloCompiler {
+    pub fn new(input: &str) -> Self {
+        let mut db = Database::default();
+        let input = input.to_string();
+        db.set_input_string((), Arc::new(input));
+        Self { db }
+    }
+
+    pub fn parse(&self) -> Arc<SyntaxTree> {
+        self.db.parse()
+    }
+
+    // should probably return an iter here
+    pub fn validate(&self) -> Vec<ApolloDiagnostic> {
+        let mut validator = Validator::new(&self.db);
+        validator.validate().into()
+    }
+
+    pub fn syntax_errors(&self) -> Vec<ApolloDiagnostic> {
+        self.db.syntax_errors()
+    }
+
+    pub fn definitions(&self) -> Arc<Vec<ast::Definition>> {
+        self.db.definitions()
+    }
+
+    pub fn operations(&self) -> values::Operations {
+        self.db.operations()
+    }
+
+    pub fn fragments(&self) -> values::Fragments {
+        self.db.fragments()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::ApolloCompiler;
+
+    #[test]
+    fn it_accesses_operation_definition_parts() {
+        let input = r#"
+query ExampleQuery($definedVariable: Int, $definedVariable2: Boolean) {
+
+  topProducts(first: $definedVariable) {
+    name
+  }
+  ... vipCustomer
+}
+
+fragment vipCustomer on User {
+  id
+  name
+  profilePic(size: 50)
+  status(activity: $definedVariable2)
+}
+"#;
+
+        let ctx = ApolloCompiler::new(input);
+        let errors = ctx.validate();
+
+        assert!(errors.is_empty());
+
+        let operations = ctx.operations();
+        let operation_names: Vec<_> = operations.iter().filter_map(|op| op.name()).collect();
+        assert_eq!(["ExampleQuery"], operation_names.as_slice());
+
+        let fragments = ctx.fragments();
+        let fragment_names: Vec<_> = fragments.iter().map(|fragment| fragment.name()).collect();
+        assert_eq!(["vipCustomer"], fragment_names.as_slice());
+
+        let operation_variables: Vec<String> = match operations.find("ExampleQuery") {
+            Some(op) => op.variables().iter().map(|var| var.name.clone()).collect(),
+            None => Vec::new(),
+        };
+        assert_eq!(
+            ["definedVariable", "definedVariable2"],
+            operation_variables.as_slice()
+        );
+    }
+}