Concrete syntax tree (CST)
Status: open/active · Aliases: CST, lossless CST
Definition
Section titled “Definition”A parse tree that keeps every token from the source — whitespace, markers, escapes, comments — not just semantic structure (an AST keeps only meaning). The full source is recoverable by concatenating the tree’s leaves in order, so a parse→serialize cycle with no edits is byte-identical. Losslessness is a property of the tree, not the parser: it cannot be retrofitted onto an AST that discarded the bytes.