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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2023-01-30 17:08:33 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2023-01-30 17:08:33 +0000 |
commit | 75d158890b303b701c51f12b34c422fb823ba9aa (patch) | |
tree | 5f10a4a1eb612918ea94a934cfc9b9893ea19442 /pdoc/docs/expressions.md | |
parent | Adding upstream version 10.5.6. (diff) | |
download | sqlglot-75d158890b303b701c51f12b34c422fb823ba9aa.tar.xz sqlglot-75d158890b303b701c51f12b34c422fb823ba9aa.zip |
Adding upstream version 10.5.10.upstream/10.5.10
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'pdoc/docs/expressions.md')
-rw-r--r-- | pdoc/docs/expressions.md | 41 |
1 files changed, 0 insertions, 41 deletions
diff --git a/pdoc/docs/expressions.md b/pdoc/docs/expressions.md deleted file mode 100644 index c82674b..0000000 --- a/pdoc/docs/expressions.md +++ /dev/null @@ -1,41 +0,0 @@ -# Expressions - -Every AST node in SQLGlot is represented by a subclass of `Expression`. Each such expression encapsulates any necessary context, such as its child expressions, their names, or arg keys, and whether each child expression is optional or not. - -Furthermore, the following attributes are common across all expressions: - -#### key - -A unique key for each class in the `Expression` hierarchy. This is useful for hashing and representing expressions as strings. - -#### args - -A dictionary used for mapping child arg keys, to the corresponding expressions. A value in this mapping is usually either a single or a list of `Expression` instances, but SQLGlot doesn't impose any constraints on the actual type of the value. - -#### arg_types - -A dictionary used for mapping arg keys to booleans that determine whether the corresponding expressions are optional or not. Consider the following example: - -```python -class Limit(Expression): - arg_types = {"this": False, "expression": True} - -``` - -Here, `Limit` declares that it expects to have one optional and one required child expression, which can be referenced through `this` and `expression`, respectively. The arg keys are generally arbitrary, but there are helper methods for keys like `this`, `expression` and `expressions` that abstract away dictionary lookups and related checks. For this reason, these keys are common throughout SQLGlot's codebase. - -#### parent - -A reference to the parent expression (may be `None`). - -#### arg_key - -The arg key an expression is associated with, i.e. the name its parent expression uses to refer to it. - -#### comments - -A list of comments that are associated with a given expression. This is used in order to preserve comments when transpiling SQL code. - -#### type - -The data type of an expression, as inferred by SQLGlot's optimizer. |