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https://github.com/hypertino/expression-parser
Expression parser and evaluator for Scala powered by parboiled2.
https://github.com/hypertino/expression-parser
expression-evaluator expression-parser parser scala
Last synced: 6 days ago
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Expression parser and evaluator for Scala powered by parboiled2.
- Host: GitHub
- URL: https://github.com/hypertino/expression-parser
- Owner: hypertino
- License: bsd-3-clause
- Created: 2016-11-10T22:09:13.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2020-01-15T10:33:10.000Z (about 5 years ago)
- Last Synced: 2023-07-01T06:02:32.104Z (over 1 year ago)
- Topics: expression-evaluator, expression-parser, parser, scala
- Language: Scala
- Homepage:
- Size: 127 KB
- Stars: 7
- Watchers: 2
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
[](https://travis-ci.org/hypertino/expression-parser)
[](https://maven-badges.herokuapp.com/maven-central/com.hypertino/expression-parser_2.13)
[ Latest releases and snapshots](https://oss.sonatype.org/#nexus-search;gav~com.hypertino~expression-parser_*~~~)
# About
This is a ready to use expression parser and evaluator for Scala powered by `parboiled2`.
Example:
```scala
val result = HEval("4*5+3*2").toInt
// result = 26
```
It's possible to provide a context with variables to the parser:
```scala
val context = Obj.from("user" -> Obj.from("count" -> 10))
val result = HEval("4*user.count+1*2", context).toInt
// result = 42
```
You also can add your own functions into the context:
```scala
val context = new ValueContext(Obj.empty) {
override def function: PartialFunction[(Identifier, Seq[Value]), Value] = {
case (Identifier(Seq("pow")), args) => args.head.toBigDecimal.pow(args.tail.head.toInt)
}
}
val result = HEval("pow(2,8)", context).toInt
// result = 256
```
## TODO
+ HParser function
## Built-in operators
`+, -, *, /` - arithmetical operations
`!, =, !=, and, or, xor` - boolean operations
`%` - remainder (modulus) operation
`>, <, >=, <=` - comparison operations
`someObject.someField` - evaluate value of 'someField' of 'someObject'
`has, has not` - tests if collection has (or has not) specified element
`like, not like` - tests if value matches regexp
`++` - adds one collection to another
`--` - computes difference between two collections
## Built-in functions
`case` - takes two arguments: index and collection. Returns value placed in collection with specified index
`isEmpty` - tests whether value is empty
`isExists` - tests whether value is present in context
`length` - returns length of collection or string. Boolean argument is a special case: function returns '1' in case of 'true' and '0' in case of 'false'
`upper, lower` - returns string in upper or lower case
`split` - takes two arguments: string and separator and returns collection made by splitting of incoming string by specified separator
`indexOf` - takes two arguments: string and substring. Returns the index within this string of the first occurrence of the specified substring
`substr` - takes 2 or 3 arguments: string, beginIndex[, endIndex] - returns substring of string
`compareIgnoreCase` - compares two strings ignoring their case
## Context field access
1. Values of fields of some object should be dot-separated:
```scala
user.field.subField
```
2. Strings can be written with quotes of apostrophes (later ignores escapes):
```scala
'someString\nabcde' // escaping ignored
"someString\nSecondLine" // newline inserted
```
3. Numbers should be written as is, without any additional symbols
## Other Examples (TODO)
```scala
user.isDefined
!user.isDefined
user.isDefined = true
user.isDefined != true
user.roles has "qa"
user.roles has not "admin"
(user.isDefined = true) and (user.roles has "qa")
(user.isDefined) and (user.roles has "qa"))
(!user.isDefined) or (user.roles has "admin")
```
# Download
```sbt
libraryDependencies += "com.hypertino" %% "expression-parser" % "0.3.0"
```
Releases published to Maven Central for Scala 2.11 - 2.13 JVM & JS (user `%%%` for Scala.js enabled projects)
Snapshots live in Sonatype repository, include it additionally:
```sbt
resolvers ++= Seq(
Resolver.sonatypeRepo("public")
)
```
# License
library is available under the BSD 3-Clause License