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Diffstat (limited to 'tests/test_utils/swc.rs')
| -rw-r--r-- | tests/test_utils/swc.rs | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/tests/test_utils/swc.rs b/tests/test_utils/swc.rs new file mode 100644 index 0000000..f455674 --- /dev/null +++ b/tests/test_utils/swc.rs @@ -0,0 +1,247 @@ +extern crate micromark; +extern crate swc_common; +extern crate swc_ecma_ast; +extern crate swc_ecma_parser; +use micromark::{MdxExpressionKind, MdxSignal}; +use swc_common::{source_map::Pos, BytePos, FileName, SourceFile, Spanned}; +use swc_ecma_ast::{EsVersion, Expr, Module}; +use swc_ecma_parser::{ + error::Error as SwcError, parse_file_as_expr, parse_file_as_module, EsConfig, Syntax, +}; + +/// Parse ESM in MDX with SWC. +#[allow(dead_code)] +pub fn parse_esm(value: &str) -> MdxSignal { + let (file, syntax, version) = create_config(value.to_string()); + let mut errors = vec![]; + let result = parse_file_as_module(&file, syntax, version, None, &mut errors); + + match result { + Err(error) => swc_error_to_signal(&error, value.len(), 0, "esm"), + Ok(tree) => { + if errors.is_empty() { + check_esm_ast(&tree) + } else { + if errors.len() > 1 { + println!("parse_esm: todo: multiple errors? {:?}", errors); + } + swc_error_to_signal(&errors[0], value.len(), 0, "esm") + } + } + } +} + +/// Parse expressions in MDX with SWC. +#[allow(dead_code)] +pub fn parse_expression(value: &str, kind: &MdxExpressionKind) -> MdxSignal { + // Empty expressions are OK. + if matches!(kind, MdxExpressionKind::Expression) + && matches!(whitespace_and_comments(0, value), MdxSignal::Ok) + { + return MdxSignal::Ok; + } + + // For attribute expression, a spread is needed, for which we have to prefix + // and suffix the input. + // See `check_expression_ast` for how the AST is verified. + let (prefix, suffix) = if matches!(kind, MdxExpressionKind::AttributeExpression) { + ("({", "})") + } else { + ("", "") + }; + + let (file, syntax, version) = create_config(format!("{}{}{}", prefix, value, suffix)); + let mut errors = vec![]; + let result = parse_file_as_expr(&file, syntax, version, None, &mut errors); + + match result { + Err(error) => swc_error_to_signal(&error, value.len(), prefix.len(), "expression"), + Ok(tree) => { + if errors.is_empty() { + let place = fix_swc_position(tree.span().hi.to_usize(), prefix.len()); + let result = check_expression_ast(&tree, kind); + if matches!(result, MdxSignal::Ok) { + whitespace_and_comments(place, value) + } else { + result + } + } else { + if errors.len() > 1 { + unreachable!("parse_expression: todo: multiple errors? {:?}", errors); + } + swc_error_to_signal(&errors[0], value.len(), prefix.len(), "expression") + } + } + } +} + +/// Check that the resulting AST of ESM is OK. +/// +/// This checks that only module declarations (import/exports) are used, not +/// statements. +fn check_esm_ast(tree: &Module) -> MdxSignal { + let mut index = 0; + while index < tree.body.len() { + let node = &tree.body[index]; + + if !node.is_module_decl() { + let place = fix_swc_position(node.span().hi.to_usize(), 0); + return MdxSignal::Error( + "Unexpected statement in code: only import/exports are supported".to_string(), + place, + ); + } + + index += 1; + } + + MdxSignal::Ok +} + +/// Check that the resulting AST of an expressions is OK. +/// +/// This checks that attribute expressions are the expected spread. +fn check_expression_ast(tree: &Expr, kind: &MdxExpressionKind) -> MdxSignal { + if matches!(kind, MdxExpressionKind::AttributeExpression) + && tree + .unwrap_parens() + .as_object() + .and_then(|object| { + if object.props.len() == 1 { + object.props[0].as_spread() + } else { + None + } + }) + .is_none() + { + MdxSignal::Error( + "Expected a single spread value, such as `...x`".to_string(), + 0, + ) + } else { + MdxSignal::Ok + } +} + +/// Turn an SWC error into an `MdxSignal`. +/// +/// * If the error happens at `value_len`, yields `MdxSignal::Eof` +/// * Else, yields `MdxSignal::Error`. +fn swc_error_to_signal( + error: &SwcError, + value_len: usize, + prefix_len: usize, + name: &str, +) -> MdxSignal { + let message = error.kind().msg().to_string(); + let place = fix_swc_position(error.span().hi.to_usize(), prefix_len); + let message = format!("Could not parse {} with swc: {}", name, message); + + if place >= value_len { + MdxSignal::Eof(message) + } else { + MdxSignal::Error(message, place) + } +} + +/// Move past JavaScript whitespace (well, actually ASCII whitespace) and +/// comments. +/// +/// This is needed because for expressions, we use an API that parses up to +/// a valid expression, but there may be more expressions after it, which we +/// don’t alow. +fn whitespace_and_comments(mut index: usize, value: &str) -> MdxSignal { + let bytes = value.as_bytes(); + let len = bytes.len(); + let mut in_multiline = false; + let mut in_line = false; + + while index < len { + // In a multiline comment: `/* a */`. + if in_multiline { + if index + 1 < len && bytes[index] == b'*' && bytes[index + 1] == b'/' { + index += 1; + in_multiline = false; + } + } + // In a line comment: `// a`. + else if in_line { + if index + 1 < len && bytes[index] == b'\r' && bytes[index + 1] == b'\n' { + index += 1; + in_line = false; + } else if bytes[index] == b'\r' || bytes[index] == b'\n' { + in_line = false; + } + } + // Not in a comment, opening a multiline comment: `/* a */`. + else if index + 1 < len && bytes[index] == b'/' && bytes[index + 1] == b'*' { + index += 1; + in_multiline = true; + } + // Not in a comment, opening a line comment: `// a`. + else if index + 1 < len && bytes[index] == b'/' && bytes[index + 1] == b'/' { + index += 1; + in_line = true; + } + // Outside comment, whitespace. + else if bytes[index].is_ascii_whitespace() { + // Fine! + } + // Outside comment, not whitespace. + else { + return MdxSignal::Error( + "Could not parse expression with swc: Unexpected content after expression" + .to_string(), + index, + ); + } + + index += 1; + } + + if in_multiline { + MdxSignal::Error( + "Could not parse expression with swc: Unexpected unclosed multiline comment, expected closing: `*/`".to_string(), + index, + ) + } else if in_line { + // EOF instead of EOL is specifically not allowed, because that would + // mean the closing brace is on the commented-out line + MdxSignal::Error( + "Could not parse expression with swc: Unexpected unclosed line comment, expected line ending: `\\n`".to_string(), + index, + ) + } else { + MdxSignal::Ok + } +} + +/// Create configuration for SWC, shared between ESM and expressions. +/// +/// This enables modern JavaScript (ES2022) + JSX. +fn create_config(source: String) -> (SourceFile, Syntax, EsVersion) { + ( + // File. + SourceFile::new( + FileName::Anon, + false, + FileName::Anon, + source, + BytePos::from_usize(1), + ), + // Syntax. + Syntax::Es(EsConfig { + jsx: true, + ..EsConfig::default() + }), + // Version. + EsVersion::Es2022, + ) +} + +/// Turn an SWC byte position from a resulting AST to an offset in the original +/// input string. +fn fix_swc_position(index: usize, prefix_len: usize) -> usize { + index - 1 - prefix_len +} |