Debug button to show Datalog AST

.gitignore

@@ -9,3 +9,5 @@ pkg/
 /mocha-setup.js
 /test-loader.js
 /test.html
+
+/crates/percival/bindings/

crates/percival-cli/src/main.rs

@@ -1,15 +1,22 @@
 //! Crate containing code for the `percival-cli` binary.
 
+use std::error::Error;
 use std::{
     fs::read_to_string,
     io::{self, Read, Write},
     path::PathBuf,
     process::{self, Command, Stdio},
 };
 
-use clap::Parser;
+use clap::{ArgEnum, Parser};
 
-use percival::{codegen::compile, errors::format_errors, parser::Grammar};
+use percival::{codegen::compile as compile_js, errors::format_errors, parser::Grammar};
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, ArgEnum, Debug)]
+enum Emitter {
+    JS,
+    Json,
+}
 
 /// Convenience CLI for testing the Percival language compiler.
 #[derive(Parser, Debug)]
@@ -22,6 +29,9 @@ struct Opt {
     /// Runs prettier and bat on the output.
     #[clap(short, long)]
     format: bool,
+
+    #[clap(short, long, arg_enum, default_value_t = Emitter::JS)]
+    emit: Emitter,
 }
 
 /// Run the main program.
@@ -49,7 +59,12 @@ fn main() {
         }
     };
 
-    match compile(&prog) {
+    let emitted: Result<String, Box<dyn Error>> = match opt.emit {
+        Emitter::JS => compile_js(&prog).map_err(|err| err.into()),
+        Emitter::Json => prog.json().map_err(|err| err.into()),
+    };
+
+    match emitted {
         Ok(js) => {
             if !opt.format {
                 println!("{}", js);

crates/percival-wasm/Cargo.toml

@@ -13,7 +13,7 @@ default = ["console_error_panic_hook"]
 [dependencies]
 console_error_panic_hook = { version = "0.1", optional = true }
 percival = { path = "../percival" }
-wasm-bindgen = "0.2"
+wasm-bindgen = { version = "0.2", features = ["serde-serialize"] }
 yansi = "0.5.0"
 
 [dev-dependencies]

crates/percival-wasm/src/lib.rs

@@ -54,6 +54,22 @@ impl CompilerResult {
         self.0.as_ref().ok().map(|(_, js)| js.clone())
     }
 
+    /// Returns the AST of the program's source.
+    pub fn ast(&self) -> JsValue {
+        self.0
+            .as_ref()
+            .ok()
+            .map(|(prog, _)| match JsValue::from_serde(prog) {
+                Ok(ast) => ast,
+                Err(err) => {
+                    // XX: wasm-bindgen claims to have errors, but doesn't
+                    eprintln!("{} {}", Paint::red("Error:"), err);
+                    JsValue::UNDEFINED
+                }
+            })
+            .unwrap_or(JsValue::UNDEFINED)
+    }
+
     /// Returns the names of relations that are dependencies of this program.
     pub fn deps(&self) -> Option<Vec<JsValue>> {
         self.0.as_ref().ok().map(|(prog, _)| {

crates/percival/Cargo.toml

@@ -9,6 +9,9 @@ ariadne = "0.1.3"
 chumsky = "0.7.0"
 rpds = "0.11.0"
 thiserror = "1.0.30"
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+ts-rs = "6.1"
 
 [dev-dependencies]
 maplit = "1.0.2"

crates/percival/src/ast.rs

@@ -1,18 +1,40 @@
 //! Abstract syntax tree definitions for the Percival language.
 
+// How to build AST types:
+//
+//    cargo test ast::export_bindings
+//    mkdir -p $(percival_wasm_pkg)/ast
+//    for ts in $(percival_bindings)/* ; do \
+//    	cp $$ts $(percival_wasm_pkg)/ast/"$$(basename "$${ts%.ts}.d.ts")" ; \
+//    done
+//    sed -i '' -e 's~ast(): any~ast(): import("./ast/Program").Program | undefined~' $(percival_wasm_pkg)/percival_wasm.d.ts
+//
+
+use serde::Serialize;
+use serde_json::{to_string_pretty, Result as JsonResult};
 use std::collections::{BTreeMap, BTreeSet};
+use ts_rs::TS;
 
 /// A program translation unit in the Percival language.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub struct Program {
     /// Rules that make up the program.
     pub rules: Vec<Rule>,
     /// Imports prefixed with the `import` keyword.
     pub imports: Vec<Import>,
 }
 
+impl Program {
+    /// Convert the program to a JSON string.
+    pub fn json(&self) -> JsonResult<String> {
+        to_string_pretty(self)
+    }
+}
+
 /// Represents a single Horn clause.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub struct Rule {
     /// Head or implicand of the Horn clause.
     pub goal: Fact,
@@ -21,7 +43,8 @@ pub struct Rule {
 }
 
 /// An element of the right-hand side of a rule.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub enum Clause {
     /// Relational assumption in the rule.
     Fact(Fact),
@@ -32,7 +55,8 @@ pub enum Clause {
 }
 
 /// Literal part of a Horn clause, written in terms of relations.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub struct Fact {
     /// Name of the relation being referenced.
     pub name: String,
@@ -41,7 +65,8 @@ pub struct Fact {
 }
 
 /// A bound or unbound value assigned to part of a relation.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub enum Value {
     /// A simple identifier, which can be either bound or unbound.
     Id(String),
@@ -54,7 +79,8 @@ pub enum Value {
 }
 
 /// Literal values supported by the Percival grammar.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub enum Literal {
     /// A standard floating-point number literal.
     Number(String),
@@ -65,7 +91,8 @@ pub enum Literal {
 }
 
 /// An aggregate operation over stratified dependency relations.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub struct Aggregate {
     /// Name of the aggregate operator, such as `min` or `sum`.
     pub operator: String,
@@ -76,7 +103,8 @@ pub struct Aggregate {
 }
 
 /// An external import from a static JSON dataset.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, TS)]
+#[ts(export)]
 pub struct Import {
     /// Name of the relation being imported.
     pub name: String,

package.json

@@ -36,6 +36,7 @@
     "remark-rehype": "^10.1.0",
     "svelte": "^3.46.6",
     "svelte-icons": "^2.1.0",
+    "svelte-json-tree": "^1.0.0",
     "unified": "^10.1.2"
   },
   "devDependencies": {