reconstruct call stack on exception

muscript/src/main/java/io/gitlab/jfronny/muscript/StandardLib.java

@@ -32,7 +32,7 @@ public class StandardLib {
                     int a1 = args.get(1).asNumber().getValue().intValue();
                     int a2 = args.get(2).asNumber().getValue().intValue();
                     return new DDate(() -> LocalDate.of(a0, a1, a2));
-                }, () -> "date")))
+                }, "date")))
                 .set("time", new DCallableObject(Map.of(
                         "now", new DTime(LocalTime::now)
                 ), DFinal.of(args -> {
@@ -43,7 +43,7 @@ public class StandardLib {
                     int a1 = args.get(1).asNumber().getValue().intValue();
                     int a2 = args.get(2).asNumber().getValue().intValue();
                     return new DTime(() -> LocalTime.of(a0, a1, a2));
-                }, () -> "time")))
+                }, "time")))
 
                 .set("round", StandardLib::round)
                 .set("floor", StandardLib::floor)

muscript/src/main/java/io/gitlab/jfronny/muscript/ast/dynamic/Bind.java

@@ -29,7 +29,7 @@ public class Bind extends DynamicExpr {
                     .asCallable()
                     .getValue()
                     .apply(DFinal.of(argsWithParameter));
-        }, this::toString);
+        }, this::toString, "<bind>");
     }
 
     @Override

muscript/src/main/java/io/gitlab/jfronny/muscript/ast/dynamic/Call.java

@@ -9,6 +9,7 @@ import io.gitlab.jfronny.muscript.data.Scope;
 import io.gitlab.jfronny.muscript.data.dynamic.*;
 import io.gitlab.jfronny.muscript.data.dynamic.additional.DFinal;
 import io.gitlab.jfronny.muscript.error.LocationalException;
+import io.gitlab.jfronny.muscript.error.StackFrame;
 
 import java.io.IOException;
 import java.util.*;
@@ -28,11 +29,21 @@ public class Call extends DynamicExpr {
 
     @Override
     public Dynamic<?> get(Scope dataRoot) {
+        DCallable dc;
+        DList arg;
         try {
-            return left.get(dataRoot)
-                    .asCallable()
-                    .getValue()
-                    .apply(DFinal.of(args.stream().flatMap(e -> e.get(dataRoot)).toArray(Dynamic[]::new)));
+            dc = left.get(dataRoot)
+                    .asCallable();
+            arg = DFinal.of(args.stream().flatMap(e -> e.get(dataRoot)).toArray(Dynamic[]::new));
+        } catch (DynamicTypeConversionException e) {
+            throw e.locational(chStart, chEnd);
+        } catch (RuntimeException e) {
+            throw new LocationalException(chStart, chEnd, "Could not perform call successfully", e);
+        }
+        try {
+            return dc.getValue().apply(arg);
+        } catch (LocationalException le) {
+            throw le.appendStack(new StackFrame.Raw(dc.getName(), left.chStart));
         } catch (DynamicTypeConversionException e) {
             throw e.locational(chStart, chEnd);
         } catch (RuntimeException e) {

muscript/src/main/java/io/gitlab/jfronny/muscript/ast/dynamic/assign/DynamicAssign.java

@@ -3,6 +3,7 @@ package io.gitlab.jfronny.muscript.ast.dynamic.assign;
 import io.gitlab.jfronny.muscript.ast.*;
 import io.gitlab.jfronny.muscript.compiler.*;
 import io.gitlab.jfronny.muscript.data.Scope;
+import io.gitlab.jfronny.muscript.data.dynamic.DCallable;
 import io.gitlab.jfronny.muscript.data.dynamic.Dynamic;
 import io.gitlab.jfronny.muscript.error.LocationalException;
 
@@ -22,7 +23,7 @@ public class DynamicAssign extends DynamicExpr {
     @Override
     public Dynamic<?> get(Scope dataRoot) {
         Dynamic<?> data = value.get(dataRoot);
-        dataRoot.set(name, data);
+        dataRoot.set(name, data instanceof DCallable callable ? callable.named(name) : data);
         return data;
     }
 

muscript/src/main/java/io/gitlab/jfronny/muscript/data/Script.java

@@ -41,7 +41,7 @@ public class Script extends Decompilable {
         return DFinal.of(args -> {
             scope.set("args", args);
             return run(scope);
-        }, () -> "{->\n" + this + "\n}()");
+        }, () -> "{->\n" + this + "\n}()", "<root>");
     }
 
     public DynamicExpr asExpr() {

muscript/src/main/java/io/gitlab/jfronny/muscript/data/dynamic/DCallable.java

@@ -1,6 +1,7 @@
 package io.gitlab.jfronny.muscript.data.dynamic;
 
 import io.gitlab.jfronny.muscript.data.dynamic.additional.DFinal;
+import io.gitlab.jfronny.muscript.data.dynamic.additional.NamedDCallable;
 
 import java.util.function.Function;
 
@@ -12,4 +13,12 @@ public non-sealed interface DCallable extends Dynamic<Function<DList, Dynamic<?>
     default Dynamic<?> call(Dynamic<?>... args) {
         return call(DFinal.of(args));
     }
+
+    default String getName() {
+        return "<unnamed>";
+    }
+
+    default DCallable named(String name) {
+        return new NamedDCallable(this, name);
+    }
 }

muscript/src/main/java/io/gitlab/jfronny/muscript/data/dynamic/additional/DFinal.java

@@ -38,7 +38,15 @@ public class DFinal {
     }
 
     public static DCallable of(Function<DList, ? extends Dynamic<?>> b, Supplier<String> serialized) {
-        return new FCallable((Function<DList, Dynamic<?>>) b, new LazySupplier<>(serialized));
+        return of(b, serialized, null);
+    }
+
+    public static DCallable of(Function<DList, ? extends Dynamic<?>> b, String name) {
+        return of(b, () -> name, name);
+    }
+
+    public static DCallable of(Function<DList, ? extends Dynamic<?>> b, Supplier<String> serialized, String name) {
+        return new FCallable((Function<DList, Dynamic<?>>) b, new LazySupplier<>(serialized), name);
     }
 
     /**
@@ -107,7 +115,7 @@ public class DFinal {
         }
     }
 
-    private record FCallable(Function<DList, Dynamic<?>> value, Supplier<String> string) implements DCallable, FImpl {
+    private record FCallable(Function<DList, Dynamic<?>> value, Supplier<String> string, String name) implements DCallable, FImpl {
         @Override
         public void serialize(ExprWriter writer) throws IOException {
             writer.append(toString());
@@ -122,5 +130,15 @@ public class DFinal {
         public String toString() {
             return string.get();
         }
+
+        @Override
+        public String getName() {
+            return name == null ? DCallable.super.getName() : name;
+        }
+
+        @Override
+        public DCallable named(String name) {
+            return new FCallable(value, string, name);
+        }
     }
 }

muscript/src/main/java/io/gitlab/jfronny/muscript/data/dynamic/additional/NamedDCallable.java

@@ -0,0 +1,29 @@
+package io.gitlab.jfronny.muscript.data.dynamic.additional;
+
+import io.gitlab.jfronny.muscript.compiler.ExprWriter;
+import io.gitlab.jfronny.muscript.data.dynamic.*;
+
+import java.io.IOException;
+import java.util.function.Function;
+
+public record NamedDCallable(DCallable inner, String name) implements DCallable {
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public DCallable named(String name) {
+        return new NamedDCallable(inner, name);
+    }
+
+    @Override
+    public void serialize(ExprWriter writer) throws IOException {
+        inner.serialize(writer);
+    }
+
+    @Override
+    public Function<DList, Dynamic<?>> getValue() {
+        return inner.getValue();
+    }
+}

muscript/src/main/java/io/gitlab/jfronny/muscript/error/LocationalError.java

@@ -2,6 +2,8 @@ package io.gitlab.jfronny.muscript.error;
 
 import org.jetbrains.annotations.Nullable;
 
+import java.util.*;
+
 /**
  * Class for storing errors with code context
  * Can be generated from a LocationalException with asPrintable
@@ -10,7 +12,11 @@ import org.jetbrains.annotations.Nullable;
  * @param start   The location of the start of this error. Both it and its components must not be null.
  * @param end     The location of the end of this error. May be null.
  */
-public record LocationalError(String message, Location start, @Nullable Location end) {
+public record LocationalError(String message, Location start, @Nullable Location end, List<? extends StackFrame> callStack) {
+    public LocationalError(String message, Location start, @Nullable Location end) {
+        this(message, start, end, List.of());
+    }
+
     /**
      * A location in the source code
      *
@@ -54,7 +60,7 @@ public record LocationalError(String message, Location start, @Nullable Location
      * @return An error using the provided information
      */
     public static LocationalError create(String source, int start, String message) {
-        return new LocationalError(message, Location.create(source, start), null);
+        return builder().setSource(source).setLocation(start).setMessage(message).build();
     }
 
     /**
@@ -67,13 +73,7 @@ public record LocationalError(String message, Location start, @Nullable Location
      * @return An error using the provided information
      */
     public static LocationalError create(String source, int start, int end, String message) {
-        if (end == start) return create(source, start, message);
-        if (end < start) {
-            int a = end;
-            end = start;
-            start = a;
-        }
-        return new LocationalError(message, Location.create(source, start), Location.create(source, end));
+        return builder().setSource(source).setLocation(start, end).setMessage(message).build();
     }
 
     /**
@@ -83,18 +83,72 @@ public record LocationalError(String message, Location start, @Nullable Location
      */
     @Override
     public String toString() {
-        if (start.column < 0) return "Error at unknown location: " + message;
-        if (end == null) return "Error at " + start + ": " + message + "\n" + start.prettyPrint() + "Here";
-        if (start.row == end.row) {
-            String linePrefix = String.format("%1$6d", start.row) + " | ";
-            return "Error at " + start + ": " + message + "\n"
-                    + linePrefix + start.line + "\n"
-                    + " ".repeat(linePrefix.length() + start.column) + "^"
-                    + "-".repeat(end.column - start.column - 1)
-                    + "^-- Here";
+        StringBuilder sb = new StringBuilder();
+        if (start.column < 0) sb.append("Error at unknown location: ").append(message);
+        else {
+            sb.append("Error at ").append(start).append(": ").append(message).append("\n");
+            if (end == null) sb.append(start.prettyPrint()).append("Here");
+            else if (start.row == end.row) {
+                String linePrefix = String.format("%1$6d", start.row) + " | ";
+                sb.append(linePrefix).append(start.line).append("\n").append(" ".repeat(linePrefix.length() + start.column)).append("^").append("-".repeat(end.column - start.column - 1)).append("^-- Here");
+            }
+            else sb.append(start.prettyPrint()).append("From here").append(end.prettyPrint()).append("to here");
+        }
+        callStack.forEach(frame -> sb.append("\n  at ").append(frame));
+        return sb.toString();
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+        private String message;
+        private Location start;
+        private @Nullable Location end;
+        private List<? extends StackFrame> callStack = List.of();
+        private String source;
+
+        public Builder setSource(String source) {
+            this.source = source;
+            return this;
+        }
+
+        public Builder setMessage(String message) {
+            this.message = message;
+            return this;
+        }
+
+        public Builder setLocation(int chStart) {
+            start = Location.create(Objects.requireNonNull(source, "source is required to set location"), chStart);
+            end = null;
+            return this;
+        }
+
+        public Builder setLocation(int chStart, int chEnd) {
+            if (chEnd == chStart) return setLocation(chStart);
+            Objects.requireNonNull(source, "source is required to set location");
+            if (chEnd < chStart) {
+                int a = chEnd;
+                chEnd = chStart;
+                chStart = a;
+            }
+            start = Location.create(source, chStart);
+            end = Location.create(source, chEnd);
+            return this;
+        }
+
+        public Builder setCallStack(List<StackFrame> callStack) {
+            this.callStack = callStack.stream()
+                    .map(frame -> frame instanceof StackFrame.Lined lined
+                            ? lined
+                            : ((StackFrame.Raw) frame).lined(Objects.requireNonNull(source, "source is required to set call stack")))
+                    .toList();
+            return this;
+        }
+
+        public LocationalError build() {
+            return new LocationalError(message, start, end, callStack);
         }
-        return "Error at " + start + ": " + message + "\n"
-                + start.prettyPrint() + "From here"
-                + end.prettyPrint() + "to here";
     }
 }

muscript/src/main/java/io/gitlab/jfronny/muscript/error/LocationalException.java

@@ -1,11 +1,15 @@
 package io.gitlab.jfronny.muscript.error;
 
+import java.util.LinkedList;
+import java.util.List;
+
 /**
  * An exception type with a location
  * For use in MuScript, can be converted to a pretty LocationalError with asPrintable
  */
 public class LocationalException extends RuntimeException {
     private final int start, end;
+    private final List<StackFrame> callStack = new LinkedList<>();
 
     public LocationalException(int start, int end) {
         super();
@@ -32,6 +36,16 @@ public class LocationalException extends RuntimeException {
     }
 
     public LocationalError asPrintable(String source) {
-        return LocationalError.create(source, start, end, getLocalizedMessage());
+        return LocationalError.builder()
+                .setSource(source)
+                .setLocation(start, end)
+                .setMessage(getLocalizedMessage())
+                .setCallStack(callStack)
+                .build();
+    }
+
+    public LocationalException appendStack(StackFrame frame) {
+        callStack.add(frame);
+        return this;
     }
 }

muscript/src/main/java/io/gitlab/jfronny/muscript/error/StackFrame.java

@@ -0,0 +1,23 @@
+package io.gitlab.jfronny.muscript.error;
+
+public sealed interface StackFrame {
+    record Raw(String name, int chStart) implements StackFrame {
+        @Override
+        public String toString() {
+            return name + " (call: character " + chStart + ")";
+        }
+
+        public Lined lined(String source) {
+            int lineStart = source.lastIndexOf('\n', chStart);
+            int lineIndex = lineStart > 0 ? (int) source.substring(0, lineStart).chars().filter(c -> c == '\n').count() : 0;
+            return new Lined(name, lineIndex + 1);
+        }
+    }
+
+    record Lined(String name, int row) implements StackFrame {
+        @Override
+        public String toString() {
+            return name + " (call: line " + row + ")";
+        }
+    }
+}

muscript/src/test/java/io/gitlab/jfronny/muscript/test/StackTraceTest.java

@@ -0,0 +1,40 @@
+package io.gitlab.jfronny.muscript.test;
+
+import io.gitlab.jfronny.muscript.StandardLib;
+import io.gitlab.jfronny.muscript.compiler.Parser;
+import io.gitlab.jfronny.muscript.error.LocationalException;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class StackTraceTest {
+    @Test
+    void stackTrace() {
+        String source = """
+                someInner = { ->
+                  throw()
+                }
+                
+                someOuter = { ->
+                  someInner()
+                }
+                
+                someOuter()
+                """;
+
+        assertEquals("""
+                Error at '(' (character 8): Could not perform call successfully
+                     1 |   throw()
+                                ^-- Here
+                  at someInner (call: line 5)
+                  at someOuter (call: line 8)""",
+                assertThrows(LocationalException.class, () -> Parser.parseScript(source)
+                        .run(StandardLib.createScope()
+                                .set("throw", args -> {
+                                    throw new IllegalArgumentException("No");
+                                })
+                        ))
+                        .asPrintable(source).toString());
+    }
+}

muscript/src/test/java/io/gitlab/jfronny/muscript/test/util/MuTestUtil.java

@@ -40,7 +40,7 @@ public class MuTestUtil {
                 .set("string", "Value")
                 .set("object", Map.of(
                         "subvalue", of(1024),
-                        "subfunc", of(v -> of(v.get(1).asNumber().getValue() * v.size()), () -> "object.subfunc"),
+                        "subfunc", of(v -> of(v.get(1).asNumber().getValue() * v.size()), "object.subfunc"),
                         "1", of("One")
                 ))
                 .set("object2", Map.of(
@@ -48,7 +48,7 @@ public class MuTestUtil {
                         "sub", of(Map.of(
                                 "val", of(10)
                         )),
-                        "stringfunc", of(v -> of(v.get(0).asString().getValue()), () -> "object2.stringfunc")
+                        "stringfunc", of(v -> of(v.get(0).asString().getValue()), "object2.stringfunc")
                 ))
                 .set("list", of(of(true), of(2), of("3")))
                 .set("numbers", of(of(1), of(2), of(3), of(4), of(5), of(6), of(7), of(8), of(9), of(10)))