Initial partial AST pretty-printer (#471)

Initial partial AST pretty-printer

CHANGELOG.md

@@ -7,10 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Changed
+- *BREAKING:* partiql-ast: changed modeling of `BagOpExpr` `setq` field to be an `Option`
+- *BREAKING:* partiql-ast: changed modeling of `GroupByExpr` `strategy` field to be an `Option`
+- *BREAKING:* partiql-ast: changed modeling of `PathStep` to split `PathExpr` to `PathIndex` (e.g., `[2]`) and `PathProject` (e.g., `.a`)
+- *BREAKING:* partiql-ast: changed modeling of `PathStep` to rename `PathWildcard` to `PathForEach` (for `[*]`)
 
 ### Added
+- partiql-ast: Pretty-printing of AST via `ToPretty` trait
 
 ### Fixed
+- Minor documentation issues
 
 ## [0.8.0]
 ### Changed

extension/partiql-extension-visualize/src/ast_to_dot.rs

@@ -631,8 +631,9 @@ impl ToDot<ast::Path> for AstToDot {
 impl ToDot<ast::PathStep> for AstToDot {
     fn to_dot(&mut self, out: &mut Scope<'_, '_>, ast: &ast::PathStep) -> Targets {
         match &ast {
-            ast::PathStep::PathExpr(e) => self.to_dot(out, e),
-            ast::PathStep::PathWildCard => vec![out.node_auto_labelled("*").id()],
+            ast::PathStep::PathProject(e) => self.to_dot(out, e),
+            ast::PathStep::PathIndex(e) => self.to_dot(out, e),
+            ast::PathStep::PathForEach => vec![out.node_auto_labelled("*").id()],
             ast::PathStep::PathUnpivot => vec![out.node_auto_labelled("Unpivot").id()],
         }
     }

partiql-ast-passes/src/name_resolver.rs

@@ -514,7 +514,8 @@ fn infer_alias(expr: &ast::Expr) -> Option<ast::SymbolPrimitive> {
     match expr {
         ast::Expr::VarRef(ast::AstNode { node, .. }) => Some(node.name.clone()),
         ast::Expr::Path(ast::AstNode { node, .. }) => match node.steps.last() {
-            Some(ast::PathStep::PathExpr(expr)) => infer_alias(&expr.index),
+            Some(ast::PathStep::PathProject(expr)) => infer_alias(&expr.index),
+            Some(ast::PathStep::PathIndex(expr)) => infer_alias(&expr.index),
             _ => None,
         },
         _ => None,

partiql-ast/Cargo.toml

@@ -9,8 +9,8 @@ readme = "../README.md"
 keywords = ["sql", "ast", "query", "compilers", "interpreters"]
 categories = ["database", "compilers", "ast-implementations"]
 exclude = [
-  "**/.git/**",
-  "**/.github/**",
+    "**/.git/**",
+    "**/.github/**",
 ]
 version.workspace = true
 edition.workspace = true
@@ -23,16 +23,19 @@ bench = false
 indexmap = { version = "1.9", default-features = false }
 rust_decimal = { version = "1.25.0", default-features = false, features = ["std"] }
 serde = { version = "1.*", features = ["derive"], optional = true }
+pretty = "0.12"
+thiserror = "1.0"
 
 [dev-dependencies]
+partiql-parser = { path = "../partiql-parser", version = "0.8" }
 
 [features]
 default = []
 serde = [
-  "dep:serde",
-  "rust_decimal/serde-with-str",
-  "rust_decimal/serde",
-  "indexmap/serde",
+    "dep:serde",
+    "rust_decimal/serde-with-str",
+    "rust_decimal/serde",
+    "indexmap/serde",
 ]
 
 [dependencies.partiql-ast-macros]

partiql-ast/src/ast.rs

@@ -283,7 +283,7 @@ pub struct BagOpExpr {
     #[visit(skip)]
     pub bag_op: BagOperator,
     #[visit(skip)]
-    pub setq: SetQuantifier,
+    pub setq: Option<SetQuantifier>,
     pub lhs: Box<AstNode<Query>>,
     pub rhs: Box<AstNode<Query>>,
 }
@@ -644,7 +644,7 @@ pub enum CallArg {
     PositionalType(Type),
     /// named argument to a function call (e.g., the `"from" : 2` in `substring(a, "from":2)`
     Named(CallArgNamed),
-    /// E.g. `AS: VARCHAR` in `CAST('abc' AS VARCHAR`
+    /// E.g. `AS: VARCHAR` in `CAST('abc' AS VARCHAR)`
     NamedType(CallArgNamedType),
 }
 
@@ -676,9 +676,10 @@ pub struct Path {
 #[derive(Visit, Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PathStep {
-    PathExpr(PathExpr),
+    PathProject(PathExpr),
+    PathIndex(PathExpr),
     #[visit(skip)]
-    PathWildCard,
+    PathForEach,
     #[visit(skip)]
     PathUnpivot,
 }
@@ -789,7 +790,7 @@ pub enum JoinSpec {
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct GroupByExpr {
     #[visit(skip)]
-    pub strategy: GroupingStrategy,
+    pub strategy: Option<GroupingStrategy>,
     pub keys: Vec<AstNode<GroupKey>>,
     #[visit(skip)]
     pub group_as_alias: Option<SymbolPrimitive>,

partiql-ast/src/lib.rs

@@ -8,4 +8,7 @@
 //! This API is currently unstable and subject to change.
 
 pub mod ast;
+
+pub mod pretty;
+
 pub mod visit;