ktav 0.7.0

Ktav — a plain configuration format. Three rules, zero indentation, zero quoting. Serde-native.
Documentation 
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//! Render one line of an array (item can be scalar, object, or nested array).

use crate::error::Result;
use crate::value::Value;

use super::helpers::{bare_item_is_pair_candidate, item_needs_raw_marker, push_indent};
use super::object::render_object_body;

/// Render one line of an array (item can be scalar, object, or nested array).
///
/// `is_root_array_first` is TRUE only for index 0 of an unwrapped Array
/// root — the sole item position exposed to § 5.0.1's root-kind
/// detection, and therefore the sole position to which § 5.9.6's /
/// § 5.9.12's first-item safeguards apply.
pub(super) fn render_array_item(
    value: &Value,
    indent: usize,
    is_root_array_first: bool,
    out: &mut String,
) -> Result<()> {
    push_indent(out, indent);
    match value {
        Value::Null => {
            out.push_str("null\n");
        }
        Value::Bool(b) => {
            out.push_str(if *b { "true" } else { "false" });
            out.push('\n');
        }
        Value::Integer(s) => {
            out.push_str(s);
            out.push('\n');
        }
        Value::Float(s) => {
            out.push_str(s);
            out.push('\n');
        }
        Value::String(s) => {
            if s.contains('\r') {
                return Err(crate::render::helpers::cr_error());
            }
            if crate::render::helpers::string_needs_multiline(s) {
                // Match pair.rs: prefer indented stripped form for
                // readability, fall back to verbatim when stripped can't
                // round-trip the content; the shared chooser errors when
                // neither form can hold the body (§ 5.6.1).
                let form = crate::render::helpers::choose_multiline_form(s, true)?;

                if matches!(form, crate::render::helpers::MultilineForm::Stripped) {
                    // Stripped form (default).
                    out.push_str("(\n");
                    let content_indent = indent + 1;
                    for line in s.split('\n') {
                        if !line.is_empty() {
                            push_indent(out, content_indent);
                            out.push_str(line);
                        }
                        out.push('\n');
                    }
                    push_indent(out, indent);
                    out.push_str(")\n");
                } else {
                    // Verbatim fallback.
                    out.push_str("((\n");
                    out.push_str(s);
                    out.push('\n');
                    push_indent(out, indent);
                    out.push_str("))\n");
                }
            } else if s.is_empty() {
                // An empty-string item would otherwise render as a bare
                // indented blank line, which the parser treats as
                // decorative and drops. Force `::` so it stays a
                // recognisable literal-string entry.
                out.push_str("::\n");
            } else {
                // § 5.9.6 / § 5.9.12: when this is the FIRST item of an
                // Array root, the bare form is additionally not used if
                // the body satisfies § 5.0.1 rule 6's phase-1
                // pair-candidate test, OR — independently of that test —
                // the body begins with U+FEFF (bare form would place it
                // at byte offset 0, where § 3.1 makes readers strip it
                // as a metadata BOM). Both exclusions sit after the
                // empty (`::`) and multi-line branches, scoped to bodies
                // whose canonical form would otherwise be bare one-line.
                if item_needs_raw_marker(s)
                    || (is_root_array_first
                        && (bare_item_is_pair_candidate(s) || s.starts_with('\u{FEFF}')))
                {
                    out.push_str(":: ");
                }
                out.push_str(s);
                out.push('\n');
            }
        }
        Value::Array(items) => {
            if items.is_empty() {
                out.push_str("[]\n");
            } else {
                out.push_str("[\n");
                for item in items {
                    // Nested items are never root-detected (§ 5.9.6).
                    render_array_item(item, indent + 1, false, out)?;
                }
                push_indent(out, indent);
                out.push_str("]\n");
            }
        }
        Value::Object(obj) => {
            if obj.is_empty() {
                out.push_str("{}\n");
            } else {
                out.push_str("{\n");
                render_object_body(obj, indent + 1, false, out)?;
                push_indent(out, indent);
                out.push_str("}\n");
            }
        }
    }
    Ok(())
}