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feat: allow filters to work on all nodes (#49)
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filter expressions can now be used on all nodes not just arrays

Closes #48

Signed-off-by: Jeff Davis <jeffda@vmware.com>
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JefeDavis authored May 28, 2021
1 parent 4dbf4b3 commit 637b8b6
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95 changes: 47 additions & 48 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -11,71 +11,70 @@ Valid paths are strings conforming to the following BNF syntax.

```
<path> ::= <identity> | <root> <subpath> | <subpath> |
<undotted child> <subpath> ; an undotted child is allowed at the start of a path
<identity> ::= "" ; the current node
<root> ::= "$" ; the root node of a document
<undotted child> <subpath> | <subpath> <filter> ; an undotted child is allowed at the start of a path
<identity> ::= "" ; the current node
<root> ::= "$" ; the root node of a document
<subpath> ::= <identity> | <child> <subpath> |
<array access> <subpath> |
<recursive descent> <subpath>
<child> ::= <dot child> | <bracket child>
<dot child> ::= "." <dotted child name> | ".*" ; named child (restricted characters) or all children
<bracket child> ::= "[" <child names> "]" | "[" <child names> "]~" ; named children | property names of children
<dot child> ::= "." <dotted child name> | ".*" ; named child (restricted characters) or all children
<bracket child> ::= "[" <child names> "]" | "[" <child names> "]~" ; named children | property names of children
<child names> ::= <child name> |
<child name> "," <child names>
<undotted child> ::= <dotted child name> | ; named child (restricted characters)
<dotted child name><array access> | ; array access of named child
<dotted child name>"~" ; property name of child
"*" ; all children
"*" <array access> ; array access of all children
<undotted child> ::= <dotted child name> | ; named child (restricted characters)
<dotted child name><array access> | ; array access of named child
<dotted child name>"~" ; property name of child
"*" ; all children
"*" <array access> ; array access of all children
<child name> ::= "'" <single quoted string> "'" |
'"' <double quoted string> '"'
<single quoted string> ::= "\'" <single quoted string> | ; escaped single quote
"\\" <single quoted string> | ; escaped backslash
<single quoted string> ::= "\'" <single quoted string> | ; escaped single quote
"\\" <single quoted string> | ; escaped backslash
<string without ' or \> <single quoted string> |
"" ; empty string
<double quoted string> ::= '\"' <double quoted string> | ; escaped double quote
'\\' <double quoted string> | ; escaped backslash
"" ; empty string
<double quoted string> ::= '\"' <double quoted string> | ; escaped double quote
'\\' <double quoted string> | ; escaped backslash
<string without " or \> <double quoted string> |
"" ; empty string
"" ; empty string
<recursive descent> ::= ".." <dotted child name> | ; all the descendants named <dotted child name>
".." <array access> ; array access of all descendents
<array access> ::= "[" union "]" | "[" <filter> "]" ; zero or more elements of a sequence
<recursive descent> ::= ".." <dotted child name> | ; all the descendants named <dotted child name>
".." <array access> | ; array access of all descendents
<array access> ::= "[" union "]" | "[" <filter> "]" ; zero or more elements of a sequence
<union> ::= <index> | <index> "," <union>
<index> ::= <integer> | <range> | "*" ; specific index, range of indices, or all indices
<range> ::= <integer> ":" <integer> | ; start (inclusive) to end (exclusive)
<integer> ":" <integer> ":" <integer> ; start (inclusive) to end (exclusive) by step
<index> ::= <integer> | <range> | "*" ; specific index, range of indices, or all indices
<range> ::= <integer> ":" <integer> | ; start (inclusive) to end (exclusive)
<integer> ":" <integer> ":" <integer> ; start (inclusive) to end (exclusive) by step
<filter> ::= "?(" <filter expr> ")"
<filter expr> ::= <filter and> |
<filter and> "||" <filter expr> ; disjunction
<filter and> "||" <filter expr> ; disjunction
<filter and> ::= <basic filter> |
<basic filter> "&&" <filter and> ; conjunction (binds more tightly than ||)
<basic filter> ::= <filter subpath> | ; subpath exists
"!" <basic filter> | ; negation
<filter term> "==" <filter term> | ; equality
<filter term> "!=" <filter term> | ; inequality
<filter term> ">" <filter term> | ; numeric greater than
<filter term> ">=" <filter term> | ; numeric greater than or equal to
<filter term> "<" <filter term> | ; numeric less than
<filter term> "<=" <filter term> | ; numeric less than or equal to
<filter subpath> "=~" <regular expr> |; subpath value matches regular expression
"(" <filter expr> ")" ; bracketing
<filter term> ::= "@" <subpath> | ; item relative to element being processed
"@" | ; value of element being processed
"$" <subpath> | ; item relative to root node of a document
<basic filter> "&&" <filter and> ; conjunction (binds more tightly than ||)
<basic filter> ::= <filter subpath> | ; subpath exists
"!" <basic filter> | ; negation
<filter term> "==" <filter term> | ; equality
<filter term> "!=" <filter term> | ; inequality
<filter term> ">" <filter term> | ; numeric greater than
<filter term> ">=" <filter term> | ; numeric greater than or equal to
<filter term> "<" <filter term> | ; numeric less than
<filter term> "<=" <filter term> | ; numeric less than or equal to
<filter subpath> "=~" <regular expr> | ; subpath value matches regular expression
"(" <filter expr> ")" ; bracketing
<filter term> ::= "@" <subpath> | ; item relative to element being processed
"@" | ; value of element being processed
"$" <subpath> | ; item relative to root node of a document
<filter literal>
<filter subpath> ::= "@" <subpath> | ; item, relative to element being processed
"$" <subpath> ; item, relative to root node of a document
<filter literal> ::= <integer> | ; positive or negative decimal integer
<floating point number> | ; floating point number
"'" <string without '> "'" | ; string enclosed in single quotes
"true" | "false" | ; boolean (must not be quoted)
"null" ; null (must not be quoted)
<regular expr> ::= "/" <go regex> "/" ; Go regular expression with any "/" in the regex escaped as "\/"
<filter subpath> ::= "@" <subpath> | ; item, relative to element being processed
"$" <subpath> ; item, relative to root node of a document
<filter literal> ::= <integer> | ; positive or negative decimal integer
<floating point number> | ; floating point number
"'" <string without '> "'" | ; string enclosed in single quotes
"true" | "false" | ; boolean (must not be quoted)
"null" ; null (must not be quoted)
<regular expr> ::= "/" <go regex> "/" ; Go regular expression with any "/" in the regex escaped as "\/"
```

The `NewPath` function parses a string path and returns a corresponding value of the `Path` type and
Expand Down Expand Up @@ -136,9 +135,9 @@ A matcher of the form `[*]` selects all the nodes in each sequence node.

### Filters: `[?()]`

This matches selects a subsequence of each sequence node in the input slice satisfying the filter expression.
This matcher selects a subset of each node in the input satisfying the filter expression.

Filter expression are composed of three kinds of term:
Filter expressions are composed of three kinds of term:
* `@` terms which produce a slice of descendants of the current node being matched (which is a node in one of the input sequences). Any path expression may be appended after the `@` to determine which descendants to include.
* `$` terms which produce a slice of descendants of the root node. Any path expression may be appended after the `$` to determine which descendants to include.
* Integer, floating point, and string literals (enclosed in single quotes, e.g. 'x').
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4 changes: 0 additions & 4 deletions pkg/yamlpath/path.go
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Original file line number Diff line number Diff line change
Expand Up @@ -426,10 +426,6 @@ func arraySubscriptThen(subscript string, p *Path) *Path {
func filterThen(filterLexemes []lexeme, p *Path) *Path {
filter := newFilter(newFilterNode(filterLexemes))
return new(func(node, root *yaml.Node) yit.Iterator {
if node.Kind != yaml.SequenceNode {
return empty(node, root)
}

its := []yit.Iterator{}
for _, c := range node.Content {
if filter(c, root) {
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