forked from kscience/kmath
123 lines
3.9 KiB
Markdown
123 lines
3.9 KiB
Markdown
# Abstract Syntax Tree Expression Representation and Operations (`kmath-ast`)
|
|
|
|
This subproject implements the following features:
|
|
|
|
- [expression-language](src/jvmMain/kotlin/kscience/kmath/ast/parser.kt) : Expression language and its parser
|
|
- [mst](src/commonMain/kotlin/kscience/kmath/ast/MST.kt) : MST (Mathematical Syntax Tree) as expression language's syntax intermediate representation
|
|
- [mst-building](src/commonMain/kotlin/kscience/kmath/ast/MstAlgebra.kt) : MST building algebraic structure
|
|
- [mst-interpreter](src/commonMain/kotlin/kscience/kmath/ast/MST.kt) : MST interpreter
|
|
- [mst-jvm-codegen](src/jvmMain/kotlin/kscience/kmath/asm/asm.kt) : Dynamic MST to JVM bytecode compiler
|
|
- [mst-js-codegen](src/jsMain/kotlin/kscience/kmath/estree/estree.kt) : Dynamic MST to JS compiler
|
|
|
|
|
|
> #### Artifact:
|
|
>
|
|
> This module artifact: `kscience.kmath:kmath-ast:0.2.0-dev-5`.
|
|
>
|
|
> Bintray release version: [  ](https://bintray.com/mipt-npm/kscience/kmath-ast/_latestVersion)
|
|
>
|
|
> Bintray development version: [  ](https://bintray.com/mipt-npm/dev/kmath-ast/_latestVersion)
|
|
>
|
|
> **Gradle:**
|
|
>
|
|
> ```gradle
|
|
> repositories {
|
|
> maven { url "https://dl.bintray.com/kotlin/kotlin-eap" }
|
|
> maven { url 'https://dl.bintray.com/mipt-npm/kscience' }
|
|
> maven { url 'https://dl.bintray.com/mipt-npm/dev' }
|
|
> maven { url 'https://dl.bintray.com/hotkeytlt/maven' }
|
|
>
|
|
> }
|
|
>
|
|
> dependencies {
|
|
> implementation 'kscience.kmath:kmath-ast:0.2.0-dev-5'
|
|
> }
|
|
> ```
|
|
> **Gradle Kotlin DSL:**
|
|
>
|
|
> ```kotlin
|
|
> repositories {
|
|
> maven("https://dl.bintray.com/kotlin/kotlin-eap")
|
|
> maven("https://dl.bintray.com/mipt-npm/kscience")
|
|
> maven("https://dl.bintray.com/mipt-npm/dev")
|
|
> maven("https://dl.bintray.com/hotkeytlt/maven")
|
|
> }
|
|
>
|
|
> dependencies {
|
|
> implementation("kscience.kmath:kmath-ast:0.2.0-dev-5")
|
|
> }
|
|
> ```
|
|
|
|
## Dynamic expression code generation
|
|
|
|
### On JVM
|
|
|
|
`kmath-ast` JVM module supports runtime code generation to eliminate overhead of tree traversal. Code generator builds
|
|
a special implementation of `Expression<T>` with implemented `invoke` function.
|
|
|
|
For example, the following builder:
|
|
|
|
```kotlin
|
|
RealField.mstInField { symbol("x") + 2 }.compile()
|
|
```
|
|
|
|
… leads to generation of bytecode, which can be decompiled to the following Java class:
|
|
|
|
```java
|
|
package kscience.kmath.asm.generated;
|
|
|
|
import java.util.Map;
|
|
import kotlin.jvm.functions.Function2;
|
|
import kscience.kmath.asm.internal.MapIntrinsics;
|
|
import kscience.kmath.expressions.Expression;
|
|
import kscience.kmath.expressions.Symbol;
|
|
|
|
public final class AsmCompiledExpression_45045_0 implements Expression<Double> {
|
|
private final Object[] constants;
|
|
|
|
public final Double invoke(Map<Symbol, Double> arguments) {
|
|
return (Double)((Function2)this.constants[0]).invoke((Double)MapIntrinsics.getOrFail(arguments, "x"), 2);
|
|
}
|
|
|
|
public AsmCompiledExpression_45045_0(Object[] constants) {
|
|
this.constants = constants;
|
|
}
|
|
}
|
|
|
|
```
|
|
|
|
### Example Usage
|
|
|
|
This API extends MST and MstExpression, so you may optimize as both of them:
|
|
|
|
```kotlin
|
|
RealField.mstInField { symbol("x") + 2 }.compile()
|
|
RealField.expression("x+2".parseMath())
|
|
```
|
|
|
|
#### Known issues
|
|
|
|
- The same classes may be generated and loaded twice, so it is recommended to cache compiled expressions to avoid
|
|
class loading overhead.
|
|
- This API is not supported by non-dynamic JVM implementations (like TeaVM and GraalVM) because of using class loaders.
|
|
|
|
### On JS
|
|
|
|
A similar feature is also available on JS.
|
|
|
|
```kotlin
|
|
RealField.mstInField { symbol("x") + 2 }.compile()
|
|
```
|
|
|
|
The code above returns expression implemented with such a JS function:
|
|
|
|
```js
|
|
var executable = function (constants, arguments) {
|
|
return constants[1](constants[0](arguments, "x"), 2);
|
|
};
|
|
```
|
|
|
|
#### Known issues
|
|
|
|
- This feature uses `eval` which can be unavailable in several environments.
|