add empty and length functions

Author: Steve Lee (POWERSHELL HE/HIM) (from Dev Box)

dsc/tests/dsc_functions.tests.ps1

@@ -159,4 +159,87 @@ Describe 'tests for function expressions' {
             ($out.results[0].result.actualState.output | Out-String) | Should -BeExactly ($expected | Out-String)
         }
     }
+
+    It 'length function works for: <expression>' -TestCases @(
+        @{ expression = "[length(parameters('array'))]" ; expected = 3 }
+        @{ expression = "[length(parameters('object'))]" ; expected = 4 }
+        @{ expression = "[length(parameters('string'))]" ; expected = 12 }
+        @{ expression = "[length('')]"; expected = 0 }
+    ) {
+        param($expression, $expected, $isError)
+
+        $config_yaml = @"
+            `$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+            parameters:
+              array:
+                type: array
+                defaultValue:
+                - a
+                - b
+                - c
+              object:
+                type: object
+                defaultValue:
+                  one: a
+                  two: b
+                  three: c
+                  four: d
+              string:
+                type: string
+                defaultValue: 'hello world!'
+            resources:
+            - name: Echo
+              type: Microsoft.DSC.Debug/Echo
+              properties:
+                output: "$expression"
+"@
+        $out = dsc -l trace config get -i $config_yaml 2>$TestDrive/error.log | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content $TestDrive/error.log -Raw)
+        ($out.results[0].result.actualState.output | Out-String) | Should -BeExactly ($expected | Out-String)
+    }
+
+    It 'empty function works for: <expression>' -TestCases @(
+        @{ expression = "[empty(parameters('array'))]" ; expected = $false }
+        @{ expression = "[empty(parameters('object'))]" ; expected = $false }
+        @{ expression = "[empty(parameters('string'))]" ; expected = $false }
+        @{ expression = "[empty(parameters('emptyArray'))]" ; expected = $true }
+        @{ expression = "[empty(parameters('emptyObject'))]" ; expected = $true }
+        @{ expression = "[empty('')]" ; expected = $true }
+    ) {
+        param($expression, $expected)
+
+        $config_yaml = @"
+            `$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+            parameters:
+              array:
+                type: array
+                defaultValue:
+                - a
+                - b
+                - c
+              emptyArray:
+                type: array
+                defaultValue: []
+              object:
+                type: object
+                defaultValue:
+                  one: a
+                  two: b
+                  three: c
+              emptyObject:
+                type: object
+                defaultValue: {}
+              string:
+                type: string
+                defaultValue: 'hello world!'
+            resources:
+            - name: Echo
+              type: Microsoft.DSC.Debug/Echo
+              properties:
+                output: "$expression"
+"@
+        $out = dsc -l trace config get -i $config_yaml 2>$TestDrive/error.log | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content $TestDrive/error.log -Raw)
+        ($out.results[0].result.actualState.output | Out-String) | Should -BeExactly ($expected | Out-String)
+    }
 }

dsc_lib/locales/en-us.toml

@@ -259,6 +259,11 @@ description = "Divides the first number by the second"
 invoked = "div function"
 divideByZero = "Cannot divide by zero"
 
+[functions.empty]
+description = "Checks if an array, object, or string is empty"
+invoked = "empty function"
+invalidArgType = "Invalid argument type, argument must be an array, object, or string"
+
 [functions.envvar]
 description = "Retrieves the value of an environment variable"
 notFound = "Environment variable not found"
@@ -297,6 +302,11 @@ parseStringError = "unable to parse string to int"
 castError = "unable to cast to int"
 parseNumError = "unable to parse number to int"
 
+[functions.length]
+description = "Returns the length of a string, array, or object"
+invoked = "length function"
+invalidArgType = "Invalid argument type, argument must be a string, array, or object"
+
 [functions.less]
 description = "Evaluates if the first value is less than the second value"
 invoked = "less function"

dsc_lib/src/functions/empty.rs

@@ -0,0 +1,75 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use core::option::Option::Some;
+
+use crate::DscError;
+use crate::configure::context::Context;
+use crate::functions::{AcceptedArgKind, Function, FunctionCategory};
+use rust_i18n::t;
+use serde_json::Value;
+use tracing::debug;
+
+#[derive(Debug, Default)]
+pub struct Empty {}
+
+impl Function for Empty {
+    fn description(&self) -> String {
+        t!("functions.empty.description").to_string()
+    }
+
+    fn category(&self) -> FunctionCategory {
+        FunctionCategory::Array
+    }
+
+    fn min_args(&self) -> usize {
+        1
+    }
+
+    fn max_args(&self) -> usize {
+        1
+    }
+
+    fn accepted_arg_types(&self) -> Vec<AcceptedArgKind> {
+        vec![AcceptedArgKind::Array, AcceptedArgKind::Object, AcceptedArgKind::String]
+    }
+
+    fn invoke(&self, args: &[Value], _context: &Context) -> Result<Value, DscError> {
+        debug!("{}", t!("functions.empty.invoked"));
+        if let Some(array) = args[0].as_array() {
+            return Ok(Value::Bool(array.is_empty()));
+        }
+
+        if let Some(object) = args[0].as_object() {
+            return Ok(Value::Bool(object.keys().len() == 0));
+        }
+
+        if let Some(string) = args[0].as_str() {
+            return Ok(Value::Bool(string.is_empty()));
+        }
+
+        Err(DscError::Parser(t!("functions.empty.invalidArgType").to_string()))
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use crate::configure::context::Context;
+    use crate::parser::Statement;
+    use serde_json::Value;
+
+    #[test]
+    fn empty_string() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[empty('')]", &Context::new()).unwrap();
+        assert_eq!(result, Value::Bool(true));
+    }
+
+    #[test]
+    fn not_empty_string() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[empty('foo')]", &Context::new()).unwrap();
+        assert_eq!(result, Value::Bool(false));
+    }
+}

dsc_lib/src/functions/length.rs

@@ -0,0 +1,75 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use core::option::Option::Some;
+
+use crate::DscError;
+use crate::configure::context::Context;
+use crate::functions::{AcceptedArgKind, Function, FunctionCategory};
+use rust_i18n::t;
+use serde_json::Value;
+use tracing::debug;
+
+#[derive(Debug, Default)]
+pub struct Length {}
+
+impl Function for Length {
+    fn description(&self) -> String {
+        t!("functions.length.description").to_string()
+    }
+
+    fn category(&self) -> FunctionCategory {
+        FunctionCategory::Array
+    }
+
+    fn min_args(&self) -> usize {
+        1
+    }
+
+    fn max_args(&self) -> usize {
+        1
+    }
+
+    fn accepted_arg_types(&self) -> Vec<AcceptedArgKind> {
+        vec![AcceptedArgKind::Array, AcceptedArgKind::Object, AcceptedArgKind::String]
+    }
+
+    fn invoke(&self, args: &[Value], _context: &Context) -> Result<Value, DscError> {
+        debug!("{}", t!("functions.length.invoked"));
+        if let Some(array) = args[0].as_array() {
+            return Ok(Value::Number(array.len().into()));
+        }
+
+        if let Some(object) = args[0].as_object() {
+            return Ok(Value::Number(object.keys().len().into()));
+        }
+
+        if let Some(string) = args[0].as_str() {
+            return Ok(Value::Number(string.len().into()));
+        }
+
+        Err(DscError::Parser(t!("functions.length.invalidArgType").to_string()))
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use crate::configure::context::Context;
+    use crate::parser::Statement;
+    use serde_json::Value;
+
+    #[test]
+    fn empty_string() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[length('')]", &Context::new()).unwrap();
+        assert_eq!(result, Value::Number(0.into()));
+    }
+
+    #[test]
+    fn not_empty_string() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[length('foo')]", &Context::new()).unwrap();
+        assert_eq!(result, Value::Number(3.into()));
+    }
+}

dsc_lib/src/functions/mod.rs

@@ -21,12 +21,14 @@ pub mod contains;
 pub mod create_array;
 pub mod create_object;
 pub mod div;
+pub mod empty;
 pub mod envvar;
 pub mod equals;
 pub mod greater;
 pub mod greater_or_equals;
 pub mod r#if;
 pub mod r#false;
+pub mod length;
 pub mod less;
 pub mod less_or_equals;
 pub mod format;
@@ -101,6 +103,7 @@ impl FunctionDispatcher {
         functions.insert("createArray".to_string(), Box::new(create_array::CreateArray{}));
         functions.insert("createObject".to_string(), Box::new(create_object::CreateObject{}));
         functions.insert("div".to_string(), Box::new(div::Div{}));
+        functions.insert("empty".to_string(), Box::new(empty::Empty{}));
         functions.insert("envvar".to_string(), Box::new(envvar::Envvar{}));
         functions.insert("equals".to_string(), Box::new(equals::Equals{}));
         functions.insert("false".to_string(), Box::new(r#false::False{}));
@@ -109,6 +112,7 @@ impl FunctionDispatcher {
         functions.insert("if".to_string(), Box::new(r#if::If{}));
         functions.insert("format".to_string(), Box::new(format::Format{}));
         functions.insert("int".to_string(), Box::new(int::Int{}));
+        functions.insert("length".to_string(), Box::new(length::Length{}));
         functions.insert("less".to_string(), Box::new(less::Less{}));
         functions.insert("lessOrEquals".to_string(), Box::new(less_or_equals::LessOrEquals{}));
         functions.insert("max".to_string(), Box::new(max::Max{}));