6.1.0: faster interpreter, Bedrock-compatible MoLang and compiler fixes

[dima-dencep]

Summary

• The interpreter is faster than Mocha's again. Interpreted math.* and @Binding calls went through a method-handle spreader built on every call; an expression with math.sin and math.cos takes 135 ns instead of 304 ns (Mocha 3.0.1: 249 ns).
• MoLang evaluates like Bedrock for everything checked in the game: grouping of = and ? :, blocks in conditionals, ??, string comparison, math.round, the random functions and empty statements.
• The compiler gives the interpreter's results and rejects what it can't compile with a clear error, instead of generating invalid bytecode or silently returning 0.
• Fixes in the network format, Java binding parameters, toString() and @BindExternalFunction; CI now builds and tests every push to main and every pull request.
• Version 6.1.0.

Every fix has regression tests; 88 tests pass.

Behaviour changes

These change what existing MoLang evaluates to. Each one was decided by Bedrock, tested in the game with a behaviour pack whose animation controllers report each result, or, where Bedrock wasn't tested, by the majority of MolangJS 1.7.1, bridge's molang 2.0.1, bedrockk/MoLang, Moonflower's molang-compiler 3.1.1.19 and molang-py 1.0.1.

Expression	6.0.2	6.1.0	Bedrock
v.x = 1 ? 5 : 6; return v.x;	1	5	5
1 ? 2 : 3 ? 4 : 5	4	2	2
v.w = 0; 1 ? { v.w = 4; } : { v.w = 5; }; return v.w;	0	4	4
v.zero = 0; return v.zero ?? 7;	7	0	0
'a' == 'b'	1	0	0
math.round(-2.5)	-2	-3	-3
math.random_integer(1, 3)	1 or 2	1 to 3	1 to 3
math.random(1, 1), math.random(5, 1)	throws	1, 1 to 5	1, 1 to 5
math.die_roll(1, 5, 6)	1.25 to 2.5	5 to 6	5 to 6
v.a = 1;; v.b = 2; return v.b;	1, the rest is dropped	2	2
math.abs(-1,), 1 +	1, 0, no error	parse error	rejected

Kept on purpose: math.sqrt(-1) and math.ln(0) still give 0 (Bedrock gives NaN and -Infinity), because a NaN that reaches a bone breaks the model. 1 / 0 is 0, as in Bedrock.

Interpreter

• ReflectiveFunction called MethodHandle.invokeWithArguments, which builds a spreader on every call. The handle is now adapted once and called with invokeExact.
• MochaMath registered a function for every binding, but didn't override set or entries(), so nothing was stored and every math.* call went through reflection. The functions now back the bindings, with the same purity; pi and e stay inlineable constants.
• warnOnReflectiveFunctionUsage printed a line on every call, even for calls that don't use reflection. It now reports each reflectively called method once. PlayerAnimationLibrary turns this option on.
• ExecutionContext, Lazy and varargs parameters of Java bindings received null, and primitive varargs threw a ClassCastException.
• A class with a single @BindExternalFunction bound nothing, because only the repeated form was read.
• A Function returning null made q.f() + 1 throw a NullPointerException.

Parser

• An empty statement, a missing operand or a trailing comma made parseSingle return null, which dropped the rest of the script or put null into the arguments.
• toString() dropped grouping parentheses, so (1 + 2) * 3 printed as 1+2*3. It now prints text that parses back into the same tree, checked on 20,000 random expressions.

Compiler

• t.* assignments failed verification in functions returning double, int or boolean.
• Fractions were converted to boolean by truncating them, so 0.5 was false in a && 1, a ? 10 : 20 and !a.
• Division by zero and NaN or infinite results now give 0, like in the interpreter.
• variable, properties of ObjectValues, ->, ??, array access, blocks, break, continue, loop, for_each, lambda functions and ExecutionContext/Lazy/varargs parameters now throw an UnsupportedOperationException that names the construct. Before, they generated invalid bytecode, and loop/for_each silently compiled to 0. a ? b without : is now supported.

Network format

• An expression containing '' couldn't be read back: ProtocolUtils.readString returns null for an empty string.
• An unknown operator ordinal was silently read as the first operator; it now throws.
• StatementExpression (break, continue) now implements equals and hashCode.

Build, CI and docs

• build.yml runs ./gradlew build on pushes to main and on pull requests, without secrets. The manual workflow is now publish.yml and runs ./gradlew build publish, so a release can't be published with failing tests.
• The test task no longer needs Node.js; CI checks that expectations.txt matches tests.txt.
• The readme and the group in gradle.properties describe mochafloats instead of Mocha 3.
• docs/ is removed: the documentation now lives only in PlayerAnimationLibrary/Documentation, published at docs.zigythebird.com/mochafloats.

Performance

JMH 1.37, JDK 25, Apple Silicon, average time per call:

Interpreted	6.0.2	6.1.0	Mocha 3.0.1
5	0.9 ns	0.9 ns	85 ns
math.sin(v.t * 50) * 45 + math.cos(v.t * 20)	304 ns	135 ns	249 ns
@Binding instance method call	174 ns	102 ns	137 ns

Compiled functions stay within about 10% of Mocha's and Moonflower's molang-compiler; the new division and NaN checks cost 0.05 to 0.6 ns per call.

🤖 Generated with Claude Code