kmath/kmath-ast/docs/README-TEMPLATE.md
2021-07-29 07:16:26 +07:00

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# Module kmath-ast
Performance and visualization extensions to MST API.
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## 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
import space.kscience.kmath.expressions.Symbol.Companion.x
import space.kscience.kmath.expressions.*
import space.kscience.kmath.operations.*
import space.kscience.kmath.asm.*
MstField { x + 2 }.compileToExpression(DoubleField)
```
... leads to generation of bytecode, which can be decompiled to the following Java class:
```java
package space.kscience.kmath.asm.generated;
import java.util.Map;
import kotlin.jvm.functions.Function2;
import space.kscience.kmath.asm.internal.MapIntrinsics;
import space.kscience.kmath.expressions.Expression;
import space.kscience.kmath.expressions.Symbol;
public final class AsmCompiledExpression_45045_0 implements Expression<Double> {
private final Object[] constants;
public final Double invoke(Map<Symbol, ? extends Double> arguments) {
return (Double) ((Function2) this.constants[0]).invoke((Double) MapIntrinsics.getOrFail(arguments, "x"), 2);
}
public AsmCompiledExpression_45045_0(Object[] constants) {
this.constants = constants;
}
}
```
#### 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
import space.kscience.kmath.expressions.Symbol.Companion.x
import space.kscience.kmath.expressions.*
import space.kscience.kmath.operations.*
import space.kscience.kmath.estree.*
MstField { x + 2 }.compileToExpression(DoubleField)
```
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);
};
```
JS also supports experimental expression optimization with [WebAssembly](https://webassembly.org/) IR generation.
Currently, only expressions inside `DoubleField` and `IntRing` are supported.
```kotlin
import space.kscience.kmath.expressions.Symbol.Companion.x
import space.kscience.kmath.expressions.*
import space.kscience.kmath.operations.*
import space.kscience.kmath.wasm.*
MstField { x + 2 }.compileToExpression(DoubleField)
```
An example of emitted Wasm IR in the form of WAT:
```lisp
(func \$executable (param \$0 f64) (result f64)
(f64.add
(local.get \$0)
(f64.const 2)
)
)
```
#### Known issues
- ESTree expression compilation uses `eval` which can be unavailable in several environments.
- WebAssembly isn't supported by old versions of browsers (see https://webassembly.org/roadmap/).
## Rendering expressions
kmath-ast also includes an extensible engine to display expressions in LaTeX or MathML syntax.
Example usage:
```kotlin
import space.kscience.kmath.ast.*
import space.kscience.kmath.ast.rendering.*
import space.kscience.kmath.misc.*
@OptIn(UnstableKMathAPI::class)
public fun main() {
val mst = "exp(sqrt(x))-asin(2*x)/(2e10+x^3)/(12)+x^(2/3)".parseMath()
val syntax = FeaturedMathRendererWithPostProcess.Default.render(mst)
val latex = LatexSyntaxRenderer.renderWithStringBuilder(syntax)
println("LaTeX:")
println(latex)
println()
val mathML = MathMLSyntaxRenderer.renderWithStringBuilder(syntax)
println("MathML:")
println(mathML)
}
```
Result LaTeX:
<div style="background-color:white;">
![](https://latex.codecogs.com/gif.latex?%5Coperatorname{exp}%5C,%5Cleft(%5Csqrt{x}%5Cright)-%5Cfrac{%5Cfrac{%5Coperatorname{arcsin}%5C,%5Cleft(2%5C,x%5Cright)}{2%5Ctimes10^{10}%2Bx^{3}}}{12}+x^{2/3})
</div>
Result MathML (can be used with MathJax or other renderers):
<details>
```html
<math xmlns="https://www.w3.org/1998/Math/MathML">
<mrow>
<mo>exp</mo>
<mspace width="0.167em"></mspace>
<mfenced open="(" close=")" separators="">
<msqrt>
<mi>x</mi>
</msqrt>
</mfenced>
<mo>-</mo>
<mfrac>
<mrow>
<mfrac>
<mrow>
<mo>arcsin</mo>
<mspace width="0.167em"></mspace>
<mfenced open="(" close=")" separators="">
<mn>2</mn>
<mspace width="0.167em"></mspace>
<mi>x</mi>
</mfenced>
</mrow>
<mrow>
<mn>2</mn>
<mo>&times;</mo>
<msup>
<mrow>
<mn>10</mn>
</mrow>
<mrow>
<mn>10</mn>
</mrow>
</msup>
<mo>+</mo>
<msup>
<mrow>
<mi>x</mi>
</mrow>
<mrow>
<mn>3</mn>
</mrow>
</msup>
</mrow>
</mfrac>
</mrow>
<mrow>
<mn>12</mn>
</mrow>
</mfrac>
<mo>+</mo>
<msup>
<mrow>
<mi>x</mi>
</mrow>
<mrow>
<mn>2</mn>
<mo>/</mo>
<mn>3</mn>
</mrow>
</msup>
</mrow>
</math>
```
</details>
It is also possible to create custom algorithms of render, and even add support of other markup languages
(see API reference).