From ce423971e6ea3b4126806eea4b6874daee9f07b2 Mon Sep 17 00:00:00 2001
From: Uko Kokņevičs
Date: Mon, 19 Aug 2024 01:15:51 +0800
Subject: Added a checker module.

NOTE: I think I should look at guava or commons for some sort of sealable Map instead of the current Scope :D
---
 .../main/java/lv/enes/orang/checker/Checker.java   | 146 +++++++++++++++++++++
 .../lv/enes/orang/checker/CheckerException.java    |   9 ++
 2 files changed, 155 insertions(+)
 create mode 100644 checker/src/main/java/lv/enes/orang/checker/Checker.java
 create mode 100644 checker/src/main/java/lv/enes/orang/checker/CheckerException.java

(limited to 'checker/src/main/java/lv')

diff --git a/checker/src/main/java/lv/enes/orang/checker/Checker.java b/checker/src/main/java/lv/enes/orang/checker/Checker.java
new file mode 100644
index 0000000..446d3f1
--- /dev/null
+++ b/checker/src/main/java/lv/enes/orang/checker/Checker.java
@@ -0,0 +1,146 @@
+package lv.enes.orang.checker;
+
+import lv.enes.orang.ast.*;
+import lv.enes.orang.core.ImmutableScope;
+import lv.enes.orang.core.Scope;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Checker implements ExpressionVisitor<Void, CheckerException>, StatementVisitor<Checker, CheckerException> {
+	private final Scope<Boolean> definitions;
+
+	public static <E> Checker of(Map<String, E> builtins) {
+		var boolMap = builtins.keySet()
+				.stream()
+				.<Map<String, Boolean>>collect(
+						HashMap::new,
+						(map, elem) -> map.put(elem, true),
+						Map::putAll
+				);
+		return new Checker(ImmutableScope.of(boolMap));
+	}
+
+	private Checker(Scope<Boolean> definitions) {
+		this.definitions = definitions;
+	}
+
+	@Override
+	public Void visitArray(ArrayExpression array) throws CheckerException {
+		for (var expr : array.items()) {
+			visit(expr);
+		}
+		return null;
+	}
+
+	@Override
+	public Void visitBoolean(BooleanLiteral expr) {
+		// Always ok
+		return null;
+	}
+
+	@Override
+	public Void visitBinaryExpression(BinaryExpression expr) throws CheckerException {
+		visit(expr.lhs());
+		visit(expr.rhs());
+		return null;
+	}
+
+	@Override
+	public Void visitCallExpression(CallExpression expr) throws CheckerException {
+		visit(expr.callee());
+		visit(expr.arg());
+		return null;
+	}
+
+	@Override
+	public Checker visitDefinition(Definition def) throws CheckerException {
+		if (definitions.hasDefinition(def.name())) {
+			throw new CheckerException(STR."Top-level definition '\{def.name()}' redefined!");
+		}
+		return new Checker(ImmutableScope.of(definitions, def.name(), true));
+	}
+
+	@Override
+	public Void visitDoExpression(DoExpression expr) throws CheckerException {
+		for (var child : expr.body()) {
+			visit(child);
+		}
+		return null;
+	}
+
+	@Override
+	public Checker visitExpression(ExpressionStatement expr) throws CheckerException {
+		visit(expr.expr());
+		return this;
+	}
+
+	@Override
+	public Void visitFnExpression(FnExpression expr) throws CheckerException {
+		var args = new HashMap<String, Boolean>();
+		for (var arg : expr.args()) {
+			args.put(arg.name, true);
+		}
+		new Checker(ImmutableScope.of(definitions, args)).visit(expr.body());
+		return null;
+	}
+
+	@Override
+	public Void visitIfElseExpression(IfElseExpression expr) throws CheckerException {
+		visit(expr.condition());
+		visit(expr.trueBranch());
+		visit(expr.falseBranch());
+		return null;
+	}
+
+	@Override
+	public Void visitIntLiteral(IntLiteral expr) {
+		// Always ok
+		return null;
+	}
+
+	@Override
+	public Void visitLetInExpression(LetInExpression expr) throws CheckerException {
+		var locals = new HashMap<String, Boolean>();
+		for (var local : expr.bindings()) {
+			locals.put(local.name(), true);
+		}
+		new Checker(ImmutableScope.of(definitions, locals)).visit(expr.body());
+		return null;
+	}
+
+	@Override
+	public Checker visitProgram(Program program) throws CheckerException {
+		var checker = this;
+		for (var stmt : program.statements()) {
+			checker = checker.visit(stmt);
+		}
+		return checker;
+	}
+
+	@Override
+	public Void visitStringLiteral(StringLiteral expr) {
+		// Always ok
+		return null;
+	}
+
+	@Override
+	public Void visitUnaryExpression(UnaryExpression expr) throws CheckerException {
+		visit(expr.child());
+		return null;
+	}
+
+	@Override
+	public Void visitVariable(VariableExpression expr) throws CheckerException {
+		if (!definitions.hasDefinition(expr.name())) {
+			throw new CheckerException(STR."Variable named '\{expr.name()}' not defined!");
+		}
+		return null;
+	}
+
+	@Override
+	public Void visitVoidExpression() {
+		// Always ok
+		return null;
+	}
+}
diff --git a/checker/src/main/java/lv/enes/orang/checker/CheckerException.java b/checker/src/main/java/lv/enes/orang/checker/CheckerException.java
new file mode 100644
index 0000000..9354f27
--- /dev/null
+++ b/checker/src/main/java/lv/enes/orang/checker/CheckerException.java
@@ -0,0 +1,9 @@
+package lv.enes.orang.checker;
+
+import lv.enes.orang.core.OrangException;
+
+public class CheckerException extends OrangException {
+	public CheckerException(String message) {
+		super(message);
+	}
+}
-- 
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