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Merge pull request #608 from triska/xml

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ADDED: load_xml/3 to load XML files from streams, files and strings.
This commit is contained in:
Mark Thom
2020-06-22 12:21:35 -03:00
committed by GitHub
parent 4603163e88 bcd6d4e8a7
commit 376c5263f0
6 changed files with 127 additions and 16 deletions
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1
Cargo.toml
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@@ -45,3 +45,4 @@ openssl = { version = "0.10.29", features = ["vendored"] }
native-tls = "0.2.4"
chrono = "0.4.11"
select = "0.4.3"
roxmltree = "0.11.0"

5
README.md
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@@ -425,8 +425,9 @@ The modules that ship with Scryer Prolog are also called
* [`http/http_open`](src/lib/http/http_open.pl) Open a stream to
read answers from web servers. HTTPS is also supported.
* [`sgml`](src/lib/sgml.pl)
`load_html/3` represents HTML documents as Prolog terms
for convenient and efficient reasoning. See also `library(xpath)`.
`load_html/3` and `load_xml/3` represent HTML and XML documents
as Prolog terms for convenient and efficient reasoning. Use
`library(xpath)` to extract information from parsed documents.
* [`xpath`](src/lib/xpath.pl)
The predicate `xpath/3` is used for convenient reasoning about
HTML and XML documents, inspired by the XPath language. This

5
src/clause_types.rs
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@@ -299,7 +299,8 @@ pub enum SystemClauseType {
Ed25519Verify,
Ed25519NewKeyPair,
Ed25519KeyPairPublicKey,
LoadHTML
LoadHTML,
LoadXML,
}
impl SystemClauseType {
@@ -498,6 +499,7 @@ impl SystemClauseType {
&SystemClauseType::Ed25519NewKeyPair => clause_name!("$ed25519_new_keypair"),
&SystemClauseType::Ed25519KeyPairPublicKey => clause_name!("$ed25519_keypair_public_key"),
&SystemClauseType::LoadHTML => clause_name!("$load_html"),
&SystemClauseType::LoadXML => clause_name!("$load_xml"),
}
}
@@ -676,6 +678,7 @@ impl SystemClauseType {
("$ed25519_new_keypair", 1) => Some(SystemClauseType::Ed25519NewKeyPair),
("$ed25519_keypair_public_key", 2) => Some(SystemClauseType::Ed25519KeyPairPublicKey),
("$load_html", 3) => Some(SystemClauseType::LoadHTML),
("$load_xml", 3) => Some(SystemClauseType::LoadXML),
_ => None,
}
}

70
src/lib/sgml.pl
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@@ -1,18 +1,23 @@
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Predicates for parsing markup documents.
Predicates for parsing HTML and XML documents.
Written June 2020 by Markus Triska (triska@metalevel.at)
Part of Scryer Prolog.
Currently, only a single predicate is provided:
Currently, two predicates are provided:
load_html(+In, -Es, +Options)
=============================
- load_html(+Source, -Es, +Options)
- load_xml(+Source, -Es, +Options)
In must be a stream, specified as stream(S), and Es is unified with
a list of elements of the form:
These predicates parse HTML and XML documents, respectively.
Source must be a stream, specified as stream(S), or a file,
specified as file(Name), where Name is a list of characters, or a
list of characters with the document contents.
Es is unified with the abstract syntax tree of the parsed document,
represented as a list of elements where each is of the form:
* a list of characters, representing text
* element(Name, Attrs, Children)
- Name is the name of the tag
- Attrs is a list of Key=Value pairs:
@@ -22,21 +27,62 @@
Currently, Options are ignored. In the future, more options may be
provided to control parsing.
Use http_open/3 from library(http/http_open) to read answers from
web servers via streams.
Example:
?- load_html("<html><head><title>Hello!</title></head></html>", Es, []).
Yielding:
Es = [element(html,[],
[element(head,[],
[element(title,[],
["Hello!"])]),
element(body,[],[])])].
library(xpath) provides convenient reasoning about parsed documents.
For example, to fetch the title of the document above, we can use:
?- load_html("<html><head><title>Hello!</title></head></html>", Es, []),
xpath(Es, //title(text), T).
Yielding T = "Hello!".
Use http_open/3 from library(http/http_open) to read answers from
web servers via streams.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
:- module(sgml, [load_html/3]).
:- module(sgml, [load_html/3,
load_xml/3]).
:- use_module(library(iso_ext)).
:- use_module(library(error)).
:- use_module(library(dcgs)).
:- use_module(library(pio)).
load_html(stream(Stream), [E], Options) :-
load_html(Source, Es, Options) :-
load_structure_(Source, Es, Options, html).
load_xml(Source, Es, Options) :-
load_structure_(Source, Es, Options, xml).
list([]) --> [].
list([L|Ls]) --> [L], list(Ls).
load_structure_([], [], _, _).
load_structure_([C|Cs], [E], Options, What) :-
load_(What, [C|Cs], E, Options).
load_structure_(file(Fs), [E], Options, What) :-
must_be(list, Options),
must_be(list, Fs),
atom_chars(File, Fs),
once(phrase_from_file(list(Cs), File)),
load_(What, Cs, E, Options).
load_structure_(stream(Stream), [E], Options, What) :-
must_be(list, Options),
read_to_end(Stream, Cs),
'$load_html'(Cs, E, []).
load_(What, Cs, E, Options).
load_(html, Cs, E, Options) :- '$load_html'(Cs, E, Options).
load_(xml, Cs, E, Options) :- '$load_xml'(Cs, E, Options).
read_to_end(Stream, Cs) :-
'$get_n_chars'(Stream, 4096, Cs0),

1
src/lib/xpath.pl
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@@ -26,7 +26,6 @@
:- use_module(library(http/http_open)).
:- use_module(library(sgml)).
:- use_module(library(format)).
:- use_module(library(lists)).
:- use_module(library(xpath)).

61
src/machine/system_calls.rs
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@@ -53,6 +53,7 @@ use crate::openssl::nid::Nid;
use crate::native_tls::TlsConnector;
extern crate select;
use roxmltree;
pub fn get_key() -> KeyEvent {
let key;
@@ -5568,11 +5569,71 @@ impl MachineState {
self.unify(self[temp_v!(2)], result);
}
&SystemClauseType::LoadXML => {
let string = self.heap_pstr_iter(self[temp_v!(1)]).to_string();
match roxmltree::Document::parse(&string) {
Ok(doc) => { let result = self.xml_node_to_term(indices, doc.root_element());
self.unify(self[temp_v!(2)], result);
}
_ => { self.fail = true;
return Ok(());
}
}
}
};
return_from_clause!(self.last_call, self)
}
pub(super)
fn xml_node_to_term(
&mut self,
indices: &mut IndexStore,
node: roxmltree::Node,
) -> Addr {
if node.has_children() {
let mut avec = Vec::new();
for attr in node.attributes() {
let chars = clause_name!(String::from(attr.name()), indices.atom_tbl);
let name = self.heap.to_unifiable(
HeapCellValue::Atom(chars, None)
);
let value = self.heap.put_complete_string(&attr.value());
avec.push(HeapCellValue::Addr(Addr::HeapCell(self.heap.h())));
self.heap.push(HeapCellValue::NamedStr(2, clause_name!("="), None));
self.heap.push(HeapCellValue::Addr(name));
self.heap.push(HeapCellValue::Addr(value));
}
let attrs = Addr::HeapCell(self.heap.to_list(avec.into_iter()));
let mut cvec = Vec::new();
for child in node.children() {
cvec.push(self.xml_node_to_term(indices, child));
}
let children = Addr::HeapCell(self.heap.to_list(cvec.into_iter()));
let chars = clause_name!(String::from(node.tag_name().name()), indices.atom_tbl);
let tag = self.heap.to_unifiable(
HeapCellValue::Atom(chars, None)
);
let result = Addr::HeapCell(self.heap.h());
self.heap.push(HeapCellValue::NamedStr(3, clause_name!("element"), None));
self.heap.push(HeapCellValue::Addr(tag));
self.heap.push(HeapCellValue::Addr(attrs));
self.heap.push(HeapCellValue::Addr(children));
result
} else {
let string = String::from(node.text().unwrap());
self.heap.put_complete_string(&string)
}
}
pub(super)
fn html_node_to_term(
&mut self,