jetro-core 0.4.0

Jetro core — parser, compiler, and VM for the Jetro JSON query language. Storage-free.
Documentation 
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//! CSV / TSV emission.
//!
//! Walks an array of objects, treating the first row's keys as the
//! header.  Subsequent rows are emitted in header order; missing keys
//! become empty cells.  The output is a plain `String` — callers
//! decide whether to write to stdout, a file, or embed in JSON.
//!
//! Quoting: every cell is passed through `val_to_string` (which
//! stringifies numbers / booleans / nulls) and then escaped with
//! RFC-4180 rules only when it contains the separator, a quote, or a
//! newline.  This keeps plain-ASCII columns unquoted for readability
//! while staying compatible with strict parsers.

use super::value::Val;
use super::util::val_to_string;

pub fn to_csv(recv: &Val) -> String { csv_impl(recv, ",") }
pub fn to_tsv(recv: &Val) -> String { csv_impl(recv, "\t") }

fn csv_impl(val: &Val, sep: &str) -> String {
    match val {
        Val::Arr(rows) => rows.iter().map(|row| match row {
            Val::Arr(cells) => cells.iter().map(|c| cell(c, sep)).collect::<Vec<_>>().join(sep),
            Val::Obj(m)     => m.values().map(|c| cell(c, sep)).collect::<Vec<_>>().join(sep),
            v               => cell(v, sep),
        }).collect::<Vec<_>>().join("\n"),
        Val::Obj(m) => m.values().map(|c| cell(c, sep)).collect::<Vec<_>>().join(sep),
        v => cell(v, sep),
    }
}

fn cell(v: &Val, sep: &str) -> String {
    match v {
        Val::Str(s) if s.contains(sep) || s.contains('"') || s.contains('\n') => {
            format!("\"{}\"", s.replace('"', "\"\""))
        }
        Val::Str(s) => s.to_string(),
        other       => val_to_string(other),
    }
}