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Diffstat (limited to 'vendor/fluent-syntax/src/parser/pattern.rs')
| -rw-r--r-- | vendor/fluent-syntax/src/parser/pattern.rs | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/vendor/fluent-syntax/src/parser/pattern.rs b/vendor/fluent-syntax/src/parser/pattern.rs new file mode 100644 index 000000000..516326d76 --- /dev/null +++ b/vendor/fluent-syntax/src/parser/pattern.rs @@ -0,0 +1,207 @@ +use super::errors::{ErrorKind, ParserError}; +use super::{core::Parser, core::Result, slice::Slice}; +use crate::ast; + +#[derive(Debug, PartialEq)] +enum TextElementTermination { + LineFeed, + CRLF, + PlaceableStart, + EOF, +} + +// This enum tracks the placement of the text element in the pattern, which is needed for +// dedentation logic. +#[derive(Debug, PartialEq)] +enum TextElementPosition { + InitialLineStart, + LineStart, + Continuation, +} + +// This enum allows us to mark pointers in the source which will later become text elements +// but without slicing them out of the source string. This makes the indentation adjustments +// cheaper since they'll happen on the pointers, rather than extracted slices. +#[derive(Debug)] +enum PatternElementPlaceholders<S> { + Placeable(ast::Expression<S>), + // (start, end, indent, position) + TextElement(usize, usize, usize, TextElementPosition), +} + +// This enum tracks whether the text element is blank or not. +// This is important to identify text elements which should not be taken into account +// when calculating common indent. +#[derive(Debug, PartialEq)] +enum TextElementType { + Blank, + NonBlank, +} + +impl<'s, S> Parser<S> +where + S: Slice<'s>, +{ + pub(super) fn get_pattern(&mut self) -> Result<Option<ast::Pattern<S>>> { + let mut elements = vec![]; + let mut last_non_blank = None; + let mut common_indent = None; + + self.skip_blank_inline(); + + let mut text_element_role = if self.skip_eol() { + self.skip_blank_block(); + TextElementPosition::LineStart + } else { + TextElementPosition::InitialLineStart + }; + + while self.ptr < self.length { + if self.take_byte_if(b'{') { + if text_element_role == TextElementPosition::LineStart { + common_indent = Some(0); + } + let exp = self.get_placeable()?; + last_non_blank = Some(elements.len()); + elements.push(PatternElementPlaceholders::Placeable(exp)); + text_element_role = TextElementPosition::Continuation; + } else { + let slice_start = self.ptr; + let mut indent = 0; + if text_element_role == TextElementPosition::LineStart { + indent = self.skip_blank_inline(); + if let Some(b) = get_current_byte!(self) { + if indent == 0 { + if b != &b'\r' && b != &b'\n' { + break; + } + } else if !Self::is_byte_pattern_continuation(*b) { + self.ptr = slice_start; + break; + } + } else { + break; + } + } + let (start, end, text_element_type, termination_reason) = self.get_text_slice()?; + if start != end { + if text_element_role == TextElementPosition::LineStart + && text_element_type == TextElementType::NonBlank + { + if let Some(common) = common_indent { + if indent < common { + common_indent = Some(indent); + } + } else { + common_indent = Some(indent); + } + } + if text_element_role != TextElementPosition::LineStart + || text_element_type == TextElementType::NonBlank + || termination_reason == TextElementTermination::LineFeed + { + if text_element_type == TextElementType::NonBlank { + last_non_blank = Some(elements.len()); + } + elements.push(PatternElementPlaceholders::TextElement( + slice_start, + end, + indent, + text_element_role, + )); + } + } + + text_element_role = match termination_reason { + TextElementTermination::LineFeed => TextElementPosition::LineStart, + TextElementTermination::CRLF => TextElementPosition::LineStart, + TextElementTermination::PlaceableStart => TextElementPosition::Continuation, + TextElementTermination::EOF => TextElementPosition::Continuation, + }; + } + } + + if let Some(last_non_blank) = last_non_blank { + let elements = elements + .into_iter() + .take(last_non_blank + 1) + .enumerate() + .map(|(i, elem)| match elem { + PatternElementPlaceholders::Placeable(expression) => { + ast::PatternElement::Placeable { expression } + } + PatternElementPlaceholders::TextElement(start, end, indent, role) => { + let start = if role == TextElementPosition::LineStart { + common_indent.map_or_else( + || start + indent, + |common_indent| start + std::cmp::min(indent, common_indent), + ) + } else { + start + }; + let mut value = self.source.slice(start..end); + if last_non_blank == i { + value.trim(); + } + ast::PatternElement::TextElement { value } + } + }) + .collect(); + return Ok(Some(ast::Pattern { elements })); + } + + Ok(None) + } + + fn get_text_slice( + &mut self, + ) -> Result<(usize, usize, TextElementType, TextElementTermination)> { + let start_pos = self.ptr; + let mut text_element_type = TextElementType::Blank; + + while let Some(b) = get_current_byte!(self) { + match b { + b' ' => self.ptr += 1, + b'\n' => { + self.ptr += 1; + return Ok(( + start_pos, + self.ptr, + text_element_type, + TextElementTermination::LineFeed, + )); + } + b'\r' if self.is_byte_at(b'\n', self.ptr + 1) => { + self.ptr += 1; + return Ok(( + start_pos, + self.ptr - 1, + text_element_type, + TextElementTermination::CRLF, + )); + } + b'{' => { + return Ok(( + start_pos, + self.ptr, + text_element_type, + TextElementTermination::PlaceableStart, + )); + } + b'}' => { + return error!(ErrorKind::UnbalancedClosingBrace, self.ptr); + } + _ => { + text_element_type = TextElementType::NonBlank; + self.ptr += 1 + } + } + } + Ok(( + start_pos, + self.ptr, + text_element_type, + TextElementTermination::EOF, + )) + } +} |