Basic visualizer for AST

Pretty-prints a representation of the AST

schala-lang/language/src/ast/mod.rs

@@ -3,11 +3,13 @@
 
 use std::{
     convert::{AsRef, From},
+    fmt,
     rc::Rc,
 };
 
 mod operators;
 mod visitor;
+mod visualize;
 
 pub use operators::{BinOp, PrefixOp};
 pub use visitor::*;
@@ -20,14 +22,6 @@ use crate::{
 
 define_id_kind!(ASTItem);
 
-/*
-#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Default)]
-pub struct ASTItem;
-impl IdKind for ASTItem {
-    fn tag() -> &'static str { "ASTItem" }
-}
-*/
-
 pub type ItemId = Id<ASTItem>;
 
 #[derive(Derivative, Debug)]
@@ -38,6 +32,12 @@ pub struct AST {
     pub statements: Block,
 }
 
+impl fmt::Display for AST {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", visualize::render_ast(self))
+    }
+}
+
 #[derive(Derivative, Debug, Clone)]
 #[derivative(PartialEq)]
 pub struct Statement {
@@ -89,6 +89,22 @@ pub struct QualifiedName {
     pub components: Vec<Rc<String>>,
 }
 
+impl fmt::Display for QualifiedName {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match &self.components[..] {
+            [] => write!(f, "[<empty>]"),
+            [name] => write!(f, "{}", name),
+            [name, rest @ ..] => {
+                write!(f, "{}", name)?;
+                for c in rest {
+                    write!(f, "::{}", c)?;
+                }
+                Ok(())
+            }
+        }
+    }
+}
+
 #[derive(Debug, PartialEq, Clone)]
 pub struct FormalParam {
     pub name: ParamName,

schala-lang/language/src/ast/visualize.rs

@@ -0,0 +1,268 @@
+use super::{
+    Block, Declaration, Expression, ExpressionKind, ImportSpecifier, InvocationArgument, ModuleSpecifier,
+    Signature, Statement, StatementKind, AST,
+};
+
+const LEVEL: usize = 2;
+
+fn do_indent(n: usize, buf: &mut String) {
+    for _ in 0..n {
+        buf.push(' ');
+    }
+}
+
+fn newline(buf: &mut String) {
+    buf.push('\n');
+}
+
+pub(super) fn render_ast(ast: &AST) -> String {
+    let AST { statements, .. } = ast;
+
+    let mut buf = format!("(AST\n");
+    render_block(&statements, LEVEL, &mut buf);
+
+    buf.push(')');
+
+    buf
+}
+
+fn render_statement(stmt: &Statement, indent: usize, buf: &mut String) {
+    use StatementKind::*;
+    do_indent(indent, buf);
+    match stmt.kind {
+        Expression(ref expr) => render_expression(expr, indent, buf),
+        Declaration(ref decl) => render_declaration(decl, indent, buf),
+        Import(ref spec) => render_import(spec, indent, buf),
+        Module(ref spec) => render_module(spec, indent, buf),
+    }
+}
+
+fn render_expression(expr: &Expression, indent: usize, buf: &mut String) {
+    use ExpressionKind::*;
+
+    buf.push_str("(Expr ");
+    match &expr.kind {
+        NatLiteral(n) => buf.push_str(&format!("(NatLiteral {})", n)),
+        FloatLiteral(f) => buf.push_str(&format!("(FloatLiteral {})", f)),
+        StringLiteral(s) => buf.push_str(&format!("(StringLiteral {})", s)),
+        BoolLiteral(b) => buf.push_str(&format!("(BoolLiteral {})", b)),
+        BinExp(binop, lhs, rhs) => {
+            let new_indent = indent + LEVEL;
+            buf.push_str(&format!("Binop {}\n", binop.sigil()));
+
+            do_indent(new_indent, buf);
+            render_expression(lhs, new_indent, buf);
+            newline(buf);
+
+            do_indent(new_indent, buf);
+            render_expression(rhs, new_indent, buf);
+            newline(buf);
+
+            do_indent(indent, buf);
+        }
+        PrefixExp(prefix, expr) => {
+            let new_indent = indent + LEVEL;
+            buf.push_str(&format!("PrefixOp {}\n", prefix.sigil()));
+
+            do_indent(new_indent, buf);
+            render_expression(expr, new_indent, buf);
+            newline(buf);
+
+            do_indent(indent, buf);
+        }
+        TupleLiteral(..) => (),
+        Value(name) => {
+            buf.push_str(&format!("Value {})", name));
+        }
+        NamedStruct { name: _, fields: _ } => (),
+        Call { f, arguments } => {
+            let new_indent = indent + LEVEL;
+            buf.push_str("Call ");
+            render_expression(f, new_indent, buf);
+            newline(buf);
+
+            for arg in arguments {
+                do_indent(new_indent, buf);
+                match arg {
+                    InvocationArgument::Positional(expr) => render_expression(expr, new_indent, buf),
+                    InvocationArgument::Keyword { .. } => buf.push_str("<keyword>"),
+                    InvocationArgument::Ignored => buf.push_str("<ignored>"),
+                }
+                newline(buf);
+                do_indent(indent, buf);
+            }
+        }
+        Index { .. } => buf.push_str("<index>"),
+        IfExpression { .. } => buf.push_str("<if-expr>"),
+        WhileExpression { .. } => buf.push_str("<while-expr>"),
+        ForExpression { .. } => buf.push_str("<for-expr>"),
+        Lambda { params, type_anno: _, body } => {
+            let new_indent = indent + LEVEL;
+            buf.push_str("Lambda ");
+            newline(buf);
+
+            do_indent(new_indent, buf);
+            buf.push_str("(Args ");
+            for p in params {
+                buf.push_str(&format!("{} ", p.name));
+            }
+            buf.push(')');
+            newline(buf);
+
+            do_indent(new_indent, buf);
+            buf.push_str("(Body ");
+            newline(buf);
+            render_block(body, new_indent + LEVEL, buf);
+            do_indent(new_indent, buf);
+            buf.push(')');
+
+            newline(buf);
+            do_indent(indent, buf);
+        }
+        ListLiteral(..) => buf.push_str("<list-literal>"),
+    }
+    buf.push(')');
+}
+fn render_declaration(decl: &Declaration, indent: usize, buf: &mut String) {
+    use Declaration::*;
+
+    buf.push_str("(Decl ");
+    match decl {
+        FuncSig(ref sig) => render_signature(sig, indent, buf),
+        FuncDecl(ref sig, ref block) => {
+            let indent = indent + LEVEL;
+            buf.push_str("Function");
+            newline(buf);
+
+            do_indent(indent, buf);
+            render_signature(sig, indent, buf);
+            newline(buf);
+
+            do_indent(indent, buf);
+            buf.push_str("(Body");
+            newline(buf);
+
+            render_block(block, indent + LEVEL, buf);
+            do_indent(indent, buf);
+            buf.push_str(")");
+            newline(buf);
+        }
+        TypeDecl { name: _, body: _, .. } => {
+            buf.push_str("<type-decl>");
+        }
+        TypeAlias { alias: _, original: _ } => {
+            buf.push_str("<type-alias>");
+        }
+        Binding { name, constant: _, type_anno: _, expr } => {
+            let new_indent = indent + LEVEL;
+            buf.push_str(&format!("Binding {}", name));
+            newline(buf);
+            do_indent(new_indent, buf);
+            render_expression(expr, new_indent, buf);
+            newline(buf);
+        }
+        _ => (), /*
+                 Impl { type_name: TypeIdentifier, interface_name: Option<TypeSingletonName>, block: Vec<Declaration> },
+                 Interface { name: Rc<String>, signatures: Vec<Signature> },
+                 Annotation { name: Rc<String>, arguments: Vec<Expression> },
+                     */
+    }
+    do_indent(indent, buf);
+    buf.push_str(")");
+}
+
+fn render_block(block: &Block, indent: usize, buf: &mut String) {
+    for stmt in block.statements.iter() {
+        render_statement(&stmt, indent, buf);
+        newline(buf);
+    }
+}
+
+fn render_signature(sig: &Signature, _indent: usize, buf: &mut String) {
+    buf.push_str(&format!("(Signature {} )", sig.name));
+}
+
+fn render_import(_import: &ImportSpecifier, _indent: usize, buf: &mut String) {
+    buf.push_str("(Import <some import>)");
+}
+fn render_module(_expr: &ModuleSpecifier, _indent: usize, buf: &mut String) {
+    buf.push_str("(Module <some mod>)");
+}
+
+#[cfg(test)]
+mod test {
+    use super::render_ast;
+    use crate::util::quick_ast;
+
+    #[test]
+    fn test_visualization() {
+        let ast = quick_ast(
+            r#"
+    fn test(x) {
+        let m = 9
+        1 * 4 <> m |> somemod::output(x)
+    }
+
+    let quincy = \(no, yes, maybe) {
+        let a = 10
+        yes * no + a
+    }
+
+    let b = 54
+    test(b) == 3
+    "#,
+        );
+
+        let expected_output = r#"(AST
+  (Decl Function
+    (Signature test )
+    (Body
+      (Decl Binding m
+        (Expr (NatLiteral 9))
+      )
+      (Expr Binop *
+        (Expr (NatLiteral 1))
+        (Expr Binop |>
+          (Expr Binop <>
+            (Expr (NatLiteral 4))
+            (Expr Value m))
+          )
+          (Expr Call (Expr Value somemod::output))
+            (Expr Value x))
+          )
+        )
+      )
+    )
+  )
+  (Decl Binding quincy
+    (Expr Lambda 
+      (Args no yes maybe )
+      (Body 
+        (Decl Binding a
+          (Expr (NatLiteral 10))
+        )
+        (Expr Binop +
+          (Expr Binop *
+            (Expr Value yes))
+            (Expr Value no))
+          )
+          (Expr Value a))
+        )
+      )
+    )
+  )
+  (Decl Binding b
+    (Expr (NatLiteral 54))
+  )
+  (Expr Binop ==
+    (Expr Call (Expr Value test))
+      (Expr Value b))
+    )
+    (Expr (NatLiteral 3))
+  )
+)"#;
+
+        let rendered = render_ast(&ast);
+        assert_eq!(rendered, expected_output);
+    }
+}