parse-book-source 0.3.1

Terminal reader for novel
Documentation
//! 规则解释器(Interpreter + Composite)。递归遍历 [`Rule`] 求值;无字符串 DSL 解析。
//!
//! 两个入口:
//! - [`eval_value`]:值规则 → 一个字符串。
//! - [`eval_list`]:列表规则 → 多个「子上下文」内容串(每个供后续 item 规则求值)。

use super::backend;
use super::error::EvalError;
use super::source::{CleanStep, Rule};
use fancy_regex::Regex;
use std::collections::HashMap;
use std::sync::LazyLock;

/// 模板插值变量表(`{{key}}` / `{{page}}` / `{{base}}` / 命名捕获)。
pub type Vars = HashMap<String, String>;

/// 对当前上下文求一个值。
pub fn eval_value(rule: &Rule, ctx: &str, vars: &Vars) -> Result<String, EvalError> {
    match rule {
        Rule::Literal { literal } => Ok(literal.clone()),
        Rule::Template { template } => Ok(interpolate(template, vars)),
        Rule::FirstOf { first_of } => {
            for r in first_of {
                let v = eval_value(r, ctx, vars)?;
                if !v.trim().is_empty() {
                    return Ok(v);
                }
            }
            Ok(String::new())
        }
        Rule::Concat { concat, join } => {
            let mut parts = Vec::new();
            for r in concat {
                let v = eval_value(r, ctx, vars)?;
                if !v.trim().is_empty() {
                    parts.push(v);
                }
            }
            Ok(parts.join(join))
        }
        Rule::Leaf(l) => {
            let raw = backend::extract(l.via, ctx, l.select.as_deref(), l.index, &l.extract)?;
            Ok(apply_clean(raw, &l.clean))
        }
    }
}

/// 选中所有匹配,返回各自的子上下文内容串。
pub fn eval_list(rule: &Rule, ctx: &str) -> Result<Vec<String>, EvalError> {
    match rule {
        Rule::Leaf(l) => match l.select.as_deref() {
            Some(sel) => backend::select_all(l.via, ctx, sel),
            // 无选择器:把当前上下文作为单一项(而非把空串当非法选择器)。
            None => Ok(vec![ctx.to_string()]),
        },
        Rule::FirstOf { first_of } => {
            for r in first_of {
                let v = eval_list(r, ctx)?;
                if !v.is_empty() {
                    return Ok(v);
                }
            }
            Ok(Vec::new())
        }
        // literal/template/concat 作为列表无意义:退化为单值(若非空)。
        other => {
            let v = eval_value(other, ctx, &Vars::new())?;
            Ok(if v.is_empty() { Vec::new() } else { vec![v] })
        }
    }
}

/// 应用清洗流水线(regex→replace、trim、prepend、append,按步顺序)。
fn apply_clean(mut s: String, steps: &[CleanStep]) -> String {
    for step in steps {
        if let Some(pat) = &step.regex
            && let Ok(re) = Regex::new(pat)
        {
            let rep = step.replace.as_deref().unwrap_or("");
            s = re.replace_all(&s, rep).into_owned();
        }
        if step.trim.unwrap_or(false) {
            s = s.trim().to_string();
        }
        if let Some(p) = &step.prepend {
            s = format!("{p}{s}");
        }
        if let Some(a) = &step.append {
            s = format!("{s}{a}");
        }
    }
    s
}

/// 把 `{{key}}` 替换为变量值,未知键替换为空串。
fn interpolate(template: &str, vars: &Vars) -> String {
    static RE: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"\{\{\s*([\w.\-]+)\s*\}\}").unwrap());
    RE.replace_all(template, |c: &fancy_regex::Captures| {
        c.get(1)
            .and_then(|m| vars.get(m.as_str()))
            .cloned()
            .unwrap_or_default()
    })
    .into_owned()
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::source::Rule;

    fn rule(j: &str) -> Rule {
        serde_json::from_str(j).expect("rule json")
    }

    // 合成的 bilixs 式目录:.box 内 直接子 h2(卷)+ a.module-row-text(章);
    // span 包裹的"阅读进度"应被 `.box > h2` 排除。
    const CATALOG: &str = r#"<html><body>
      <div class="box">
        <span id="shuqian"><h2 class="module-title type">阅读进度</h2></span>
        <h2 class="module-title type">第一卷 魔性不改</h2>
        <div class="module-row-info"><a class="module-row-text" href="/n/1.html"><i></i><div class="module-row-title"><span>第一章 甲</span></div></a></div>
        <div class="module-row-info"><a class="module-row-text" href="/n/2.html"><i></i><div class="module-row-title"><span>第二章 乙</span></div></a></div>
        <h2 class="module-title type">第二卷 魔子出山</h2>
        <div class="module-row-info"><a class="module-row-text" href="/n/3.html"><i></i><div class="module-row-title"><span>第三章 丙</span></div></a></div>
      </div>
    </body></html>"#;

    fn toc_list() -> Rule {
        rule(r#"{"via":"css","select":".box > h2.module-title.type, .box a.module-row-text"}"#)
    }

    #[test]
    fn list_selects_volumes_and_chapters_in_document_order() {
        let items = eval_list(&toc_list(), CATALOG).unwrap();
        assert_eq!(items.len(), 5, "2 卷 + 3 章 = 5(排除 span 内的阅读进度)");
    }

    #[test]
    fn toc_rules_split_into_volumes_and_chapters() {
        let name = rule(
            r#"{"firstOf":[{"via":"css","select":".module-row-title","extract":"text"},{"via":"css","select":"h2","extract":"text"}]}"#,
        );
        let url = rule(r#"{"via":"css","select":"a","extract":{"attr":"href"}}"#);
        let is_volume = rule(r#"{"via":"css","select":"h2","extract":"text"}"#);
        let vars = Vars::new();

        let mut chapters = Vec::new();
        let mut volumes = Vec::new();
        for it in eval_list(&toc_list(), CATALOG).unwrap() {
            let nm = eval_value(&name, &it, &vars).unwrap();
            if eval_value(&is_volume, &it, &vars)
                .unwrap()
                .trim()
                .is_empty()
            {
                let u = eval_value(&url, &it, &vars).unwrap();
                chapters.push((nm, u));
            } else {
                volumes.push(nm);
            }
        }
        assert_eq!(volumes, vec!["第一卷 魔性不改", "第二卷 魔子出山"]);
        assert_eq!(chapters.len(), 3);
        assert_eq!(
            chapters[0],
            ("第一章 甲".to_string(), "/n/1.html".to_string())
        );
        assert_eq!(
            chapters[2],
            ("第三章 丙".to_string(), "/n/3.html".to_string())
        );
    }

    #[test]
    fn book_info_extracts_og_meta_attr() {
        let html = r#"<head><meta property="og:novel:book_name" content="蛊真人"><meta property="og:image" content="https://x/c.jpg"></head>"#;
        let name = rule(
            r#"{"via":"css","select":"[property=\"og:novel:book_name\"]","extract":{"attr":"content"}}"#,
        );
        assert_eq!(eval_value(&name, html, &Vars::new()).unwrap(), "蛊真人");
    }

    #[test]
    fn content_html_extract_cleans_paragraphs() {
        let html = r#"<div class="article-content"><p>第一段。</p><p>第二段。</p></div>"#;
        let r = rule(
            r#"{"via":"css","select":".article-content","extract":"html","clean":[{"trim":true}]}"#,
        );
        let out = eval_value(&r, html, &Vars::new()).unwrap();
        assert!(out.contains("第一段。"));
        assert!(out.contains("第二段。"));
        assert!(out.contains('\n'), "段落间应有换行");
    }

    #[test]
    fn template_interpolates_vars() {
        let r = rule(r#"{"template":"{{base}}/search?q={{key}}&pg={{page}}"}"#);
        let mut vars = Vars::new();
        vars.insert("base".into(), "https://x.com".into());
        vars.insert("key".into(), "蛊真人".into());
        vars.insert("page".into(), "2".into());
        assert_eq!(
            eval_value(&r, "", &vars).unwrap(),
            "https://x.com/search?q=蛊真人&pg=2"
        );
    }

    #[test]
    fn firstof_falls_back_to_second_when_first_empty() {
        let r = rule(
            r#"{"firstOf":[{"via":"css","select":".nope","extract":"text"},{"via":"css","select":"h2","extract":"text"}]}"#,
        );
        let html = r#"<h2>标题</h2>"#;
        assert_eq!(eval_value(&r, html, &Vars::new()).unwrap(), "标题");
    }

    #[test]
    fn clean_regex_replace_strips_boilerplate() {
        let r = rule(
            r#"{"via":"raw","clean":[{"regex":"请收藏本站[^\\n]*","replace":""},{"trim":true}]}"#,
        );
        let out = eval_value(&r, "正文内容 请收藏本站xxx.com", &Vars::new()).unwrap();
        assert_eq!(out, "正文内容");
    }
}