support slice function

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
-name = "gtmpl"
+name = "gtmpl-moyan"
 version = "0.7.1"
-authors = ["Florian Dieminger <me@fiji-flo.de>"]
+authors = ["Florian Dieminger <me@fiji-flo.de>", "moyan <moyan@moyanjdc.top>"]
 description = "The Golang Templating Language for Rust"
 license = "MIT"
 repository = "https://github.com/fiji-flo/gtmpl-rust"

src/funcs.rs

@@ -37,6 +37,7 @@ pub static BUILTINS: &[(&str, Func)] = &[
     ("printf", printf as Func),
     ("index", index as Func),
     ("call", call as Func),
+    ("slice", slice as Func),
 ];
 
 macro_rules! val {
@@ -545,6 +546,78 @@ fn cmp(left: &Value, right: &Value) -> Option<Ordering> {
     }
 }
 
+pub fn slice(args: &[Value]) -> Result<Value, FuncError> {
+    if args.is_empty() {
+        return Err(FuncError::ExactlyXArgs("slice".to_string(), 1));
+    }
+    match &args[0] {
+        Value::String(s) => {
+            let mut indices = Vec::new();
+            for arg in &args[1..] {
+                if let Value::Number(n) = arg {
+                    if let Some(i) = n.as_i64() {
+                        indices.push(i as usize);
+                    } else {
+                        return Err(FuncError::Generic("slice bounds out of range".to_string()));
+                    }
+                } else {
+                    return Err(FuncError::Generic(
+                        "slice bounds must be numbers".to_string(),
+                    ));
+                }
+            }
+            let result = match indices.len() {
+                0 => s.clone(),
+                1 => s[indices[0]..].to_string(),
+                2 => s[indices[0]..indices[1]].to_string(),
+                3 => {
+                    // Go 语法中的 x[1:2:3] 在 Rust 中不直接支持 capacity，
+                    // 这里简化处理，只取 slice[1..2]
+                    if indices[0] <= indices[1] && indices[1] <= s.len() {
+                        s[indices[0]..indices[1]].to_string()
+                    } else {
+                        return Err(FuncError::Generic("slice bounds out of range".to_string()));
+                    }
+                }
+                _ => return Err(FuncError::ExactlyXArgs("a".to_string(), 4)),
+            };
+            Ok(Value::String(result))
+        }
+        Value::Array(arr) => {
+            let mut indices = Vec::new();
+            for arg in &args[1..] {
+                if let Value::Number(n) = arg {
+                    if let Some(i) = n.as_i64() {
+                        indices.push(i as usize);
+                    } else {
+                        return Err(FuncError::Generic("slice bounds out of range".to_string()));
+                    }
+                } else {
+                    return Err(FuncError::Generic(
+                        "slice bounds must be numbers".to_string(),
+                    ));
+                }
+            }
+            let result = match indices.len() {
+                0 => arr.clone(),
+                1 => arr[indices[0]..].to_vec(),
+                2 => arr[indices[0]..indices[1]].to_vec(),
+                3 => {
+                    // 同样简化处理
+                    if indices[0] <= indices[1] && indices[1] <= arr.len() {
+                        arr[indices[0]..indices[1]].to_vec()
+                    } else {
+                        return Err(FuncError::Generic("slice bounds out of range".to_string()));
+                    }
+                }
+                _ => return Err(FuncError::ExactlyXArgs("Doesn't engouh arg".to_string(), 4)),
+            };
+            Ok(Value::Array(result))
+        }
+        _ => Err(FuncError::Generic("slice".to_string())),
+    }
+}
+
 #[cfg(test)]
 mod tests_mocked {
     use super::*;

src/node.rs

@@ -507,7 +507,6 @@ node!(NumberNode {
 });
 
 impl NumberNode {
-    #[cfg_attr(feature = "cargo-clippy", allow(clippy::float_cmp))]
     pub fn new(
         tr: TreeId,
         pos: Pos,

tests/define.rs

@@ -1,5 +1,5 @@
-use gtmpl::{Context, Template};
 use gtmpl_derive::Gtmpl;
+use gtmpl_moyan::{Context, Template};
 
 #[test]
 fn simple_define() {

tests/niladic.rs

@@ -1,6 +1,6 @@
 use anyhow::anyhow;
-use gtmpl::{Func, FuncError, Value};
 use gtmpl_derive::Gtmpl;
+use gtmpl_moyan::{Func, FuncError, Value};
 
 fn plus_one(args: &[Value]) -> Result<Value, FuncError> {
     if let Value::Object(ref o) = &args[0] {
@@ -22,6 +22,6 @@ struct AddMe {
 #[test]
 fn simple_niladic_method() {
     let add_me = AddMe { num: 42, plus_one };
-    let output = gtmpl::template("The answer is: {{ .plus_one }}", add_me);
+    let output = gtmpl_moyan::template("The answer is: {{ .plus_one }}", add_me);
     assert_eq!(&output.unwrap(), "The answer is: 43");
 }