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use crate::scanner::*;
use crate::token::{Token, TokenKind};
pub struct JsonScanner;
fn at(b: &[u8], i: usize) -> u8 {
if i < b.len() { b[i] } else { 0 }
}
impl Scanner for JsonScanner {
fn scan(&self, code: &str) -> Vec<Token> {
let b = code.as_bytes();
let mut tokens = Vec::new();
let mut i = 0;
while i < b.len() {
let c = b[i];
if c == b' ' || c == b'\t' || c == b'\n' || c == b'\r' {
i += 1;
continue;
}
// JSONC comments
if let Some(end) = scan_c_comment(b, i) {
tokens.push(Token {
kind: TokenKind::Comment,
start: i,
end,
});
i = end;
continue;
}
// Strings (keys vs values determined by context: key if followed by :)
if c == b'"'
&& let Some(end) = scan_double_string(b, i)
{
// Check if this is a key (followed by :)
let after = skip_whitespace_no_newline(b, end);
let kind = if at(b, after) == b':' {
TokenKind::Property
} else {
TokenKind::String
};
tokens.push(Token {
kind,
start: i,
end,
});
i = end;
continue;
}
// Numbers
if c.is_ascii_digit() || (c == b'-' && at(b, i + 1).is_ascii_digit()) {
let start = i;
if c == b'-' {
i += 1;
}
if let Some(end) = scan_number(b, i) {
tokens.push(Token {
kind: TokenKind::Number,
start,
end,
});
i = end;
continue;
}
i = start;
}
// Keywords: true, false, null
if let Some((end, ident)) = scan_ident(b, i) {
let kind = match ident {
b"true" | b"false" | b"null" => TokenKind::Keyword,
_ => TokenKind::Plain,
};
tokens.push(Token {
kind,
start: i,
end,
});
i = end;
continue;
}
// Punctuation
if matches!(c, b'{' | b'}' | b'[' | b']' | b':' | b',') {
tokens.push(Token {
kind: TokenKind::Punctuation,
start: i,
end: i + 1,
});
i += 1;
continue;
}
i += 1;
}
tokens
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::token::render;
fn hl(code: &str) -> String {
let tokens = JsonScanner.scan(code);
render(code, &tokens)
}
#[test]
fn key_value() {
let out = hl(r#"{"key": "value"}"#);
assert!(out.contains("tok-property")); // key
assert!(out.contains("tok-string")); // value
}
#[test]
fn numbers() {
let out = hl(r#"{"n": 42}"#);
assert!(out.contains("tok-number"));
}
#[test]
fn booleans_null() {
let out = hl(r#"{"a": true, "b": false, "c": null}"#);
assert!(out.contains("tok-keyword"));
}
#[test]
fn nested() {
let out = hl(r#"{"a": {"b": [1, 2]}}"#);
assert!(out.contains("tok-property"));
assert!(out.contains("tok-number"));
}
#[test]
fn jsonc_comment() {
let out = hl(r#"// comment
{"key": 1}"#);
assert!(out.contains("tok-comment"));
}
}