ekt/src/main/kotlin/net/shadowfacts/ekt/EKT.kt

89 lines
2.3 KiB
Kotlin

package net.shadowfacts.ekt
import java.io.File
import javax.script.ScriptContext
import javax.script.ScriptEngineManager
/**
* @author shadowfacts
*/
object EKT {
private val startControlCodes: Map<String, (String) -> String> = mapOf(
":" to { s -> s },
"=" to { s -> ")" + s },
"#" to { s -> "*/" + s }
)
private val endControlCodes: Map<String, (String) -> String> = mapOf(
":" to { s -> s },
"=" to { s -> s + "echo(" },
"#" to { s -> s + "/*" }
)
private val startStringRegex = Regex("(?:^|[^\\\\])([:=#])]")
private val endStringRegex = Regex("\\[([:=#])")
private val scriptPrefix = """
val _result = StringBuilder()
fun echo(s: Any) { _result.append(s) }
"""
private val scriptSuffix = """
_result.toString()
"""
private val manager by lazy {
ScriptEngineManager()
}
fun render(template: String, data: Map<String, Any>, dumpGeneratedScript: File? = null): String {
@Suppress("NAME_SHADOWING")
var template = template
template = template.replace("$", "\${'$'}")
template = ":]$template[:"
template = template.replace(startStringRegex, {
val c = it.groups[1]!!.value
if (c in startControlCodes) {
startControlCodes[c]!!("\necho(\"\"\"")
} else {
throw RuntimeException("Unknown control code: [$c")
}
})
template = template.replace(endStringRegex, {
val c = it.groups[1]!!.value
if (c in endControlCodes) {
endControlCodes[c]!!("\"\"\")\n")
} else {
throw RuntimeException("Unknown control code: $c]")
}
})
val script = scriptPrefix + template + scriptSuffix
dumpGeneratedScript?.apply {
if (!exists()) createNewFile()
writeText(script)
}
return eval(script, data) as String
}
fun render(template: File, data: Map<String, Any>, dumpGeneratedScript: File? = null): String {
return render(template.readText(), data, dumpGeneratedScript)
}
internal fun eval(script: String, data: Map<String, Any> = mapOf()): Any? {
val engine = manager.getEngineByExtension("kts")
val bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE)
bindings.putAll(data)
// Hack to allow data to be accessed by name from template instead of via bindings map
val unwrapBindings = data.keys.map {
val type = data[it]!!::class.qualifiedName
"val $it = bindings[\"$it\"] as $type;"
}.joinToString("\n")
engine.eval(unwrapBindings)
return engine.eval(script)
}
}