remove unmaintained json crate, do our own string escaping

Cargo.lock

@@ -1059,12 +1059,6 @@ dependencies = [
  "wasm-bindgen",
 ]
 
-[[package]]
-name = "json"
-version = "0.12.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "078e285eafdfb6c4b434e0d31e8cfcb5115b651496faca5749b88fafd4f23bfd"
-
 [[package]]
 name = "language-tags"
 version = "0.3.2"
@@ -1416,7 +1410,6 @@ dependencies = [
  "actix-web",
  "bytes",
  "futures",
- "json",
  "lazy_static",
  "log",
  "pdf",

Cargo.toml

@@ -12,7 +12,6 @@ actix-files = "0.6.0"
 actix-web = "4.0.1"
 bytes = "1.1"
 futures = "0.3"
-json = "0.12.4"
 lazy_static = "1.4"
 log = "0.4.16"
 pdf = "0.8"

src/serialize.rs

@@ -66,7 +66,7 @@ impl DataFormat for Csv {
     fn header(dataset: &DataSet) -> SerializationChunk {
         let mut header = String::from("Date");
         for column in dataset.columns.iter() {
-            write!(&mut header, ",{}", column)?;
+            write!(&mut header, r#","{}""#, column.replace('"', r#""""#))?;
         }
         writeln!(&mut header)?;
         Ok(header)
@@ -97,7 +97,7 @@ impl DataFormat for Json {
     fn header(dataset: &DataSet) -> SerializationChunk {
         let mut header = String::from(r#"{"columns":["Date""#);
         for column in dataset.columns.iter() {
-            write!(&mut header, ",{}", json::stringify(column.as_str()))?;
+            write!(&mut header, ",{}", escaped_json_string(column.as_str()))?;
         }
         write!(&mut header, r#"],"rows":["#)?;
         Ok(header)
@@ -115,7 +115,7 @@ impl DataFormat for Json {
         )?;
         for column in dataset.columns.iter() {
             if let Some(val) = datapoint.values.get(column) {
-                write!(&mut row, ",{}:{}", json::stringify(column.as_str()), val)?;
+                write!(&mut row, ",{}:{}", escaped_json_string(column.as_str()), val)?;
             }
         }
         row += "}";
@@ -125,3 +125,20 @@ impl DataFormat for Json {
     const ROW_SEPARATOR: &'static str = ",";
     const END: &'static str = "]}";
 }
+
+fn escaped_json_string(s: &str) -> String {
+    s.chars().fold(String::from(r#"""#), |mut acc, c| {
+        match c {
+            '"' => acc.push_str(r#"\""#),
+            '\\' => acc.push_str(r"\\"),
+            '\t' => acc.push_str(r"\t"),
+            '\n' => acc.push_str(r"\n"),
+            _ => if c.is_ascii_control() {
+                acc.push_str(&format!(r"\u{:04X}", c as u32))
+            } else {
+                acc.push(c)
+            }
+        }
+        acc
+    }) + r#"""#
+}