perf(filamento): use `with_capacity` intializers where possible

1 files changed, 81 insertions, 43 deletions

diff --git a/filamento/src/caps.rs b/filamento/src/caps.rs
index 36b2b72..ed0cd7d 100644
--- a/filamento/src/caps.rs
+++ b/filamento/src/caps.rs
@@ -5,7 +5,8 @@ use sha1::Sha1;
 use sha2::{Digest, Sha256};
 use sha3::Sha3_256;
 use stanza::{
-    xep_0030::info,
+    xep_0004,
+    xep_0030::{self, info},
     xep_0115::{self, C},
     xep_0300::{self, Algo, Hash},
     xep_0390,
@@ -57,17 +58,26 @@ pub fn caps(node: String, query: info::Query) -> Result<xep_0115::C, CapsEncodeE
     let mut string = String::new();
 
     // identities string
-    let mut identities = Vec::new();
+    let mut identities = Vec::with_capacity(query.identities.len());
     for identity in query.identities {
-        let mut string = String::new();
-        string.push_str(&identity.category);
+        let (category, r#type, lang, name) = (
+            identity.category,
+            identity.r#type,
+            identity.lang.unwrap_or_default(),
+            identity.name.unwrap_or_default(),
+        );
+
+        let mut string =
+            String::with_capacity(category.len() + r#type.len() + lang.len() + name.len() + 4);
+        string.push_str(&category);
         string.push('/');
-        string.push_str(&identity.r#type);
+        string.push_str(&r#type);
         string.push('/');
-        string.push_str(&identity.lang.unwrap_or_default());
+        string.push_str(&lang);
         string.push('/');
-        string.push_str(&identity.name.unwrap_or_default());
+        string.push_str(&name);
         string.push('<');
+
         identities.push(string);
     }
     identities.sort();
@@ -75,11 +85,12 @@ pub fn caps(node: String, query: info::Query) -> Result<xep_0115::C, CapsEncodeE
     string.push_str(&identities_string);
 
     // features string
-    let mut features = Vec::new();
-    for feature in query.features {
-        let mut string = String::new();
-        string.push_str(&feature.var);
+    let mut features = Vec::with_capacity(query.features.len());
+    for xep_0030::info::Feature { var, .. } in query.features {
+        let mut string = String::with_capacity(var.len() + 1);
+        string.push_str(&var);
         string.push('<');
+
         features.push(string);
     }
     features.sort();
@@ -87,9 +98,8 @@ pub fn caps(node: String, query: info::Query) -> Result<xep_0115::C, CapsEncodeE
     string.push_str(&features_string);
 
     // extensions string
-    let mut extensions = Vec::new();
+    let mut extensions = Vec::with_capacity(query.extensions.len());
     for extension in query.extensions {
-        let mut string = String::new();
         let form_type = extension
             .fields
             .iter()
@@ -101,31 +111,41 @@ pub fn caps(node: String, query: info::Query) -> Result<xep_0115::C, CapsEncodeE
             .map(|value| value.0)
             .collect::<Vec<String>>()
             .concat();
-        string.push_str(&form_type);
-        string.push('<');
-        let mut fields = Vec::new();
+
+        let mut fields = Vec::with_capacity(extension.fields.len());
         for field in extension.fields {
             if field.var.as_deref() == Some("FORM_TYPE") {
                 continue;
             }
-            let mut string = String::new();
-            string.push_str(&field.var.unwrap_or_default());
-            string.push('<');
-            let mut values = Vec::new();
-            for value in field.values {
-                let mut string = String::new();
-                string.push_str(&value.0);
+
+            let var = field.var.unwrap_or_default();
+
+            let mut values = Vec::with_capacity(field.values.len());
+            for xep_0004::Value(value) in field.values {
+                let mut string = String::with_capacity(value.len() + 1);
+                string.push_str(&value);
                 string.push('<');
+
                 values.push(string);
             }
             values.sort();
             let values_string = values.concat();
+
+            let mut string = String::with_capacity(var.len() + values_string.len() + 1);
+            string.push_str(&var);
+            string.push('<');
             string.push_str(&values_string);
+
             fields.push(string);
         }
         fields.sort();
         let fields_string = fields.concat();
+
+        let mut string = String::with_capacity(form_type.len() + fields_string.len() + 1);
+        string.push_str(&form_type);
+        string.push('<');
         string.push_str(&fields_string);
+
         extensions.push(string);
     }
     extensions.sort();
@@ -153,11 +173,12 @@ pub fn encode_caps2(query: info::Query) -> String {
     let mut string = String::new();
 
     // features string
-    let mut features = Vec::new();
-    for feature in query.features {
-        let mut string = String::new();
-        string.push_str(&feature.var);
+    let mut features = Vec::with_capacity(query.features.len());
+    for xep_0030::info::Feature { var, .. } in query.features {
+        let mut string = String::with_capacity(var.len() + 1);
+        string.push_str(&var);
         string.push('\x1f');
+
         features.push(string);
     }
     features.sort();
@@ -166,18 +187,27 @@ pub fn encode_caps2(query: info::Query) -> String {
     string.push('\x1c');
 
     // identities string
-    let mut identities = Vec::new();
+    let mut identities = Vec::with_capacity(query.identities.len());
     for identity in query.identities {
-        let mut string = String::new();
-        string.push_str(&identity.category);
+        let (category, r#type, lang, name) = (
+            identity.category,
+            identity.r#type,
+            identity.lang.unwrap_or_default(),
+            identity.name.unwrap_or_default(),
+        );
+
+        let mut string =
+            String::with_capacity(category.len() + r#type.len() + lang.len() + name.len() + 5);
+        string.push_str(&category);
         string.push('\x1f');
-        string.push_str(&identity.r#type);
+        string.push_str(&r#type);
         string.push('\x1f');
-        string.push_str(&identity.lang.unwrap_or_default());
+        string.push_str(&lang);
         string.push('\x1f');
-        string.push_str(&identity.name.unwrap_or_default());
+        string.push_str(&name);
         string.push('\x1f');
         string.push('\x1e');
+
         identities.push(string);
     }
     identities.sort();
@@ -186,37 +216,45 @@ pub fn encode_caps2(query: info::Query) -> String {
     string.push('\x1c');
 
     // extensions string
-    let mut extensions = Vec::new();
+    let mut extensions = Vec::with_capacity(query.extensions.len());
     for extension in query.extensions {
-        let mut string = String::new();
-        let mut fields = Vec::new();
+        let mut fields = Vec::with_capacity(extension.fields.len());
         for field in extension.fields {
-            let mut string = String::new();
-            string.push_str(&field.var.unwrap_or_default());
-            string.push('\x1f');
-            let mut values = Vec::new();
-            for value in field.values {
-                let mut string = String::new();
-                string.push_str(&value.0);
+            let var = field.var.unwrap_or_default();
+
+            let mut values = Vec::with_capacity(field.values.len());
+            for xep_0004::Value(value) in field.values {
+                let mut string = String::with_capacity(value.len() + 1);
+                string.push_str(&value);
                 string.push('\x1f');
+
                 values.push(string);
             }
             values.sort();
             let values_string = values.concat();
+
+            let mut string = String::with_capacity(var.len() + values_string.len() + 2);
+            string.push_str(&var);
+            string.push('\x1f');
             string.push_str(&values_string);
             string.push('\x1e');
+
             fields.push(string);
         }
         fields.sort();
         let fields_string = fields.concat();
+
+        let mut string = String::with_capacity(fields_string.len() + 1);
         string.push_str(&fields_string);
         string.push('\x1d');
+
         extensions.push(string);
     }
     extensions.sort();
     let extensions_string = extensions.concat();
     string.push_str(&extensions_string);
     string.push('\x1c');
+
     string
 }