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#### 34.6.2 Finding the Parse State for a Position

For syntactic analysis, such as in indentation, often the useful thing is to compute the syntactic state corresponding to a given buffer position. This function does that conveniently.

Function: syntax-ppss &optional pos

  This function returns the parser state that the parser would reach at position pos starting from the beginning of the buffer. See Parser State, for a description of the parser state.

  The return value is the same as if you call the low-level parsing function `parse-partial-sexp` to parse from the beginning of the buffer to pos (see Low-Level Parsing). However, `syntax-ppss` uses a cache to speed up the computation. Due to this optimization, the second value (previous complete subexpression) and sixth value (minimum parenthesis depth) in the returned parser state are not meaningful.

  This function has a side effect: it adds a buffer-local entry to `before-change-functions` (see Change Hooks) for `syntax-ppss-flush-cache` (see below). This entry keeps the cache consistent as the buffer is modified. However, the cache might not be updated if `syntax-ppss` is called while `before-change-functions` is temporarily let-bound, or if the buffer is modified without running the hook, such as when using `inhibit-modification-hooks`. In those cases, it is necessary to call `syntax-ppss-flush-cache` explicitly.

Function: syntax-ppss-flush-cache beg &rest ignored-args

  This function flushes the cache used by `syntax-ppss`, starting at position beg. The remaining arguments, ignored-args, are ignored; this function accepts them so that it can be directly used on hooks such as `before-change-functions` (see Change Hooks).

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