Add several functions for simple expressions (#407)

Co-authored-by: elkowar <5300871+elkowar@users.noreply.github.com>
Co-authored-by: MartinJM <>

CHANGELOG.md

@@ -27,6 +27,7 @@ All notable changes to eww will be listed here, starting at changes since versio
 - Add `scroll` widget (By: viandoxdev)
 - Add `notification` window type
 - Add drag and drop functionality to eventbox
+- Add `search`, `captures`, `stringlength`, `arraylength` and `objectlength` functions for expressions (By: MartinJM, ElKowar)
 
 ### Notable Internal changes
 - Rework state management completely, now making local state and dynamic widget hierarchy changes possible.

crates/simplexpr/src/dynval.rs

@@ -14,7 +14,7 @@ pub struct ConversionError {
 }
 
 impl ConversionError {
-    fn new(value: DynVal, target_type: &'static str, source: impl std::error::Error + 'static + Sync + Send) -> Self {
+    pub fn new(value: DynVal, target_type: &'static str, source: impl std::error::Error + 'static + Sync + Send) -> Self {
         ConversionError { value, target_type, source: Some(Box::new(source)) }
     }
 }
@@ -214,6 +214,22 @@ impl DynVal {
         serde_json::from_str::<serde_json::Value>(&self.0)
             .map_err(|e| ConversionError::new(self.clone(), "json-value", Box::new(e)))
     }
+
+    pub fn as_json_array(&self) -> Result<Vec<serde_json::Value>> {
+        serde_json::from_str::<serde_json::Value>(&self.0)
+            .map_err(|e| ConversionError::new(self.clone(), "json-value", Box::new(e)))?
+            .as_array()
+            .cloned()
+            .ok_or_else(|| ConversionError { value: self.clone(), target_type: "json-array", source: None })
+    }
+
+    pub fn as_json_object(&self) -> Result<serde_json::Map<String, serde_json::Value>> {
+        serde_json::from_str::<serde_json::Value>(&self.0)
+            .map_err(|e| ConversionError::new(self.clone(), "json-value", Box::new(e)))?
+            .as_object()
+            .cloned()
+            .ok_or_else(|| ConversionError { value: self.clone(), target_type: "json-object", source: None })
+    }
 }
 
 #[cfg(test)]

crates/simplexpr/src/eval.rs

@@ -5,7 +5,10 @@ use crate::{
     dynval::{ConversionError, DynVal},
 };
 use eww_shared_util::{Span, Spanned, VarName};
-use std::{collections::HashMap, convert::TryFrom};
+use std::{
+    collections::HashMap,
+    convert::{TryFrom, TryInto},
+};
 
 #[derive(Debug, thiserror::Error)]
 pub enum EvalError {
@@ -276,6 +279,46 @@ fn call_expr_function(name: &str, args: Vec<DynVal>) -> Result<DynVal, EvalError
             }
             _ => Err(EvalError::WrongArgCount(name.to_string())),
         },
+        "search" => match args.as_slice() {
+            [string, pattern] => {
+                use serde_json::Value;
+                let string = string.as_string()?;
+                let pattern = regex::Regex::new(&pattern.as_string()?)?;
+                Ok(Value::Array(pattern.find_iter(&string).map(|x| Value::String(x.as_str().to_string())).collect())
+                    .try_into()?)
+            }
+            _ => Err(EvalError::WrongArgCount(name.to_string())),
+        },
+        "captures" => match args.as_slice() {
+            [string, pattern] => {
+                use serde_json::Value;
+                let string = string.as_string()?;
+                let pattern = regex::Regex::new(&pattern.as_string()?)?;
+                Ok(Value::Array(
+                    pattern
+                        .captures_iter(&string)
+                        .map(|captures| {
+                            Value::Array(captures.iter().flatten().map(|x| Value::String(x.as_str().to_string())).collect())
+                        })
+                        .collect(),
+                )
+                .try_into()?)
+            }
+            _ => Err(EvalError::WrongArgCount(name.to_string())),
+        },
+        "strlength" => match args.as_slice() {
+            [string] => Ok(DynVal::from(string.as_string()?.len() as i32)),
+            _ => Err(EvalError::WrongArgCount(name.to_string())),
+        },
+        "arraylength" => match args.as_slice() {
+            [json] => Ok(DynVal::from(json.as_json_array()?.len() as i32)),
+            _ => Err(EvalError::WrongArgCount(name.to_string())),
+        },
+        "objectlength" => match args.as_slice() {
+            [json] => Ok(DynVal::from(json.as_json_object()?.len() as i32)),
+            _ => Err(EvalError::WrongArgCount(name.to_string())),
+        },
+
         _ => Err(EvalError::UnknownFunction(name.to_string())),
     }
 }

docs/src/expression_language.md

@@ -32,4 +32,8 @@ Supported currently are the following features:
 - some function calls:
     - `round(number, decimal_digits)`: Round a number to the given amount of decimals
     - `replace(string, regex, replacement)`: Replace matches of a given regex in a string
+	- `search(string, regex)`: Search for a given regex in a string (returns array)
+	- `captures(string, regex)`: Get the captures of a given regex in a string (returns array)
+	- `hex_decode(string)`: Hex decodes the string
+	- `length(value)`: Gets the length of the value, as string length, json array length, or json object length