From c0f11d84bf9ed80561c1da1f478d3628408657b3 Mon Sep 17 00:00:00 2001
From: Andre Masella <andre@masella.name>
Date: Fri, 9 Feb 2024 13:20:31 -0500
Subject: [PATCH] Add `Count` operator

This expression returns the number of items in a set.
---
 changes/add_count_expression.md               |  1 +
 language.md                                   |  5 ++
 .../gsi/shesmu/compiler/ExpressionNode.java   |  1 +
 .../shesmu/compiler/ExpressionNodeCount.java  | 73 +++++++++++++++++++
 .../src/test/resources/run/count.shesmu       |  4 +
 5 files changed, 84 insertions(+)
 create mode 100644 changes/add_count_expression.md
 create mode 100644 shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNodeCount.java
 create mode 100644 shesmu-server/src/test/resources/run/count.shesmu

diff --git a/changes/add_count_expression.md b/changes/add_count_expression.md
new file mode 100644
index 000000000..500fd68ba
--- /dev/null
+++ b/changes/add_count_expression.md
@@ -0,0 +1 @@
+* Add new `Count` operator for lists
diff --git a/language.md b/language.md
index d45ab33b1..d2c8335e4 100644
--- a/language.md
+++ b/language.md
@@ -894,6 +894,11 @@ Compute the logical complement of the expression, which must be a boolean.
 
 Computes the arithmetic additive inverse of the expression, which must be an integer.
 
+#### List Size
+- `Count` _expr_
+
+Counts the number of elements _expr_, which must be a list.
+
 #### WDL Pair Conversion
 - `ConvertWdlPair` _expr_
 
diff --git a/shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNode.java b/shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNode.java
index 889aa5f3d..574f4c17e 100644
--- a/shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNode.java
+++ b/shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNode.java
@@ -658,6 +658,7 @@ private static Parser parse9(Parser input, Consumer<ExpressionNode> output) {
     UNARY.addSymbol("!", just(ExpressionNodeLogicalNot::new));
     UNARY.addSymbol("-", just(ExpressionNodeNegate::new));
     UNARY.addKeyword("ConvertWdlPair", just(ExpressionNodeWdlPair::new));
+    UNARY.addKeyword("Count", just(ExpressionNodeCount::new));
 
     SUFFIX_TIGHT.addSymbol(
         "[",
diff --git a/shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNodeCount.java b/shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNodeCount.java
new file mode 100644
index 000000000..a42ce0e3c
--- /dev/null
+++ b/shesmu-server/src/main/java/ca/on/oicr/gsi/shesmu/compiler/ExpressionNodeCount.java
@@ -0,0 +1,73 @@
+package ca.on.oicr.gsi.shesmu.compiler;
+
+import ca.on.oicr.gsi.shesmu.compiler.Target.Flavour;
+import ca.on.oicr.gsi.shesmu.plugin.types.Imyhat;
+import ca.on.oicr.gsi.shesmu.plugin.types.Imyhat.ListImyhat;
+import java.nio.file.Path;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+import org.objectweb.asm.Type;
+import org.objectweb.asm.commons.Method;
+
+public class ExpressionNodeCount extends ExpressionNode {
+
+  private static final Type A_SET_TYPE = Type.getType(Set.class);
+  private static final Method METHOD_SET__SIZE = new Method("size", Type.INT_TYPE, new Type[] {});
+  private final ExpressionNode inner;
+
+  public ExpressionNodeCount(int line, int column, ExpressionNode inner) {
+    super(line, column);
+    this.inner = inner;
+  }
+
+  @Override
+  public void collectFreeVariables(Set<String> names, Predicate<Flavour> predicate) {
+    inner.collectFreeVariables(names, predicate);
+  }
+
+  @Override
+  public void collectPlugins(Set<Path> pluginFileNames) {
+    inner.collectPlugins(pluginFileNames);
+  }
+
+  @Override
+  public void render(Renderer renderer) {
+    inner.render(renderer);
+    renderer.methodGen().invokeInterface(A_SET_TYPE, METHOD_SET__SIZE);
+    renderer.methodGen().cast(Type.INT_TYPE, Type.LONG_TYPE);
+  }
+
+  @Override
+  public String renderEcma(EcmaScriptRenderer renderer) {
+    return "(" + inner.renderEcma(renderer) + ").length";
+  }
+
+  @Override
+  public boolean resolve(NameDefinitions defs, Consumer<String> errorHandler) {
+    return inner.resolve(defs, errorHandler);
+  }
+
+  @Override
+  public boolean resolveDefinitions(
+      ExpressionCompilerServices expressionCompilerServices, Consumer<String> errorHandler) {
+    return inner.resolveDefinitions(expressionCompilerServices, errorHandler);
+  }
+
+  @Override
+  public Imyhat type() {
+    return Imyhat.INTEGER;
+  }
+
+  @Override
+  public boolean typeCheck(Consumer<String> errorHandler) {
+    var ok = inner.typeCheck(errorHandler);
+    if (ok) {
+      ok = inner.type() instanceof ListImyhat || inner.type().equals(Imyhat.EMPTY);
+      if (!ok) {
+        typeError("list", inner.type(), errorHandler);
+      }
+    }
+    return ok;
+  }
+}
diff --git a/shesmu-server/src/test/resources/run/count.shesmu b/shesmu-server/src/test/resources/run/count.shesmu
new file mode 100644
index 000000000..784076bf6
--- /dev/null
+++ b/shesmu-server/src/test/resources/run/count.shesmu
@@ -0,0 +1,4 @@
+Version 1;
+Input test;
+
+Olive Run ok With ok = (Count [] == 0) && (Count [3] == 1);