Migrated source code from Simantics SVN

[simantics/platform.git] / bundles / org.simantics.scl.compiler / src / org / simantics / scl / compiler / types / kinds / Kind.java

diff --git a/bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/types/kinds/Kind.java b/bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/types/kinds/Kind.java
new file mode 100644 (file)
index 0000000..b0c166b
--- /dev/null
+++ b/bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/types/kinds/Kind.java
@@ -0,0 +1,53 @@
+package org.simantics.scl.compiler.types.kinds;
+
+import org.simantics.scl.compiler.types.util.TypeUnparsingContext;
+
+/**
+ * This is an abstract base class for type kinds. It has three child classes:
+ * KCon for constants, KArrow for kind arrows and KMetaVar for kind meta-variables.
+ * 
+ * Child classes need to implement the method {@link #contains(KMetaVar)}, which
+ * returns true, if a given kind meta-variable points to this instance.
+ * 
+ * The default implementation of {@link #toString()} is infinitely recursive, with
+ * {@link #toString(TypeUnparsingContext, StringBuilder)} and {@link #toStringPar(TypeUnparsingContext, StringBuilder)}
+ * both calling each other. 
+ */
+public abstract class Kind {
+    public static final Kind[] EMPTY_ARRAY = new Kind[0];
+    
+    @Override
+    public String toString() {
+        return toString(new TypeUnparsingContext());
+    }
+
+    public String toString(TypeUnparsingContext tuc) {
+        StringBuilder b = new StringBuilder();
+        toString(tuc, b);
+        return b.toString();
+    }
+
+    /**
+     * Write this kind to a string builder as an unparenthesized expression.
+     * If a subclass does not need parenthesis, it can implement the
+     * {@link #toStringPar(TypeUnparsingContext, StringBuilder)} method instead.
+     */
+    protected void toString(TypeUnparsingContext tuc, StringBuilder b) {
+        toStringPar(tuc, b);
+    }
+    
+    /**
+     * Write this kind to a string builder as an atomic expression. The default implementation
+     * encloses the output of {@link #toString(TypeUnparsingContext, StringBuilder)} in parenthesis.
+     */
+    protected void toStringPar(TypeUnparsingContext tuc, StringBuilder b) {
+        b.append("(");
+        toString(tuc, b);
+        b.append(")");
+    }
+
+    /**
+     * Return true, if this kind has been unified with the given kind meta-variable.
+     */
+    public abstract boolean contains(KMetaVar var);
+}